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Number

1,681

  • Positive
  • Odd
  • Composite
  • Perfect square
  • 4 digits

1,681 is an odd 4-digit integer and a composite number. It has 3 divisors and a digital root of 7.

Number properties

ParityOddnot divisible by 2
SignPositive
PrimalityComposite
Absolute value1,681
Digit count4
Digit sum16
Digital root7repeated digit sum
PalindromicNoreads differently backwards
Perfect squareYes, 41²
Happy numberNosquared-digit sums reach 1
Harshad numberNodivisible by its own digit sum

Factors & divisors

Prime factorisation41^2
Distinct prime factors141
Number of divisors3
Sum of divisors σ(n)1,723
Aliquot sum42sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)1,640integers below n that share no factor with it
SquarefreeNohas a repeated prime factor
All divisors1, 41, 1,6813 in total

Arithmetic

Previous number1,680
Next number1,682
Double3,362
Half840.5
Square2,825,761
Cube4,750,104,241
Square root41exact
Cube root11.890202137≈
Negation-1,681
Reciprocal0.000594884≈

Representations

Decimal1,681
Binary1101001000111 bits
Octal3221
Hexadecimal691
Base 361AP
Roman numeralMDCLXXXI
In wordsone thousand, six hundred and eighty-one
Ordinalone thousand, six hundred and eighty-first
Scientific notation1.681 × 10^3
Engineering notation1.681 × 10^3

Nearest landmarks

Next prime1,693+12
Previous prime1,669−12
Distance to nearest prime12
Nearest square below1,681
Nearest square above1,764

Powers & multiples

1,681 to the power 22,825,761
1,681 to the power 34,750,104,241
1,681 to the power 47,984,925,229,121
1,681 to the power 513,422,659,310,152,401
First ten multiples1,681, 3,362, 5,043, 6,724, 8,405, 10,086, 11,767, 13,448, 15,129, 16,810
Powers of twoBetween 2^10 (1,024) and 2^11 (2,048)

Divisibility tests

Divisible by 2No, remainder 1
Divisible by 3No, remainder 1
Divisible by 4No, remainder 1
Divisible by 5No, remainder 1
Divisible by 6No, remainder 1
Divisible by 7No, remainder 1
Divisible by 8No, remainder 1
Divisible by 9No, remainder 7
Divisible by 10No, remainder 1
Divisible by 11No, remainder 9
Divisible by 12No, remainder 1
Divisible by 100No, remainder 81

Collatz (3n + 1) trajectory

Steps to reach 142the total stopping time
Highest value reached5,0443× the starting value
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps1,681 → 5,044 → 2,522 → 1,261 → 3,784 → 1,892 → 946 → 473 → 1,420 → 710 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1

As a percentage & fraction

As a percentage168,100%
1,681% as a decimal16.81
1,681% of 1001,681
1,681% of 1,00016,810
As a fraction of 1001,681/100

Read another way

As seconds28 minutes and 1 second
As bytes1.642 KiB
As a year1681 AD
As a 24-bit colour#000691

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Neighbouring numbers

Nearby primes

Also reads as

1681 (year)

  • Common year
  • 365 days
  • 17th century
  • Rooster

1681 was a common year of 365 days. It began on a Wednesday and ended on a Wednesday. Easter Sunday fell on 6 April.

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Structure of the year

Leap yearNonot divisible by 4
Days in the year365
Weeks in the year52ISO 8601 weeks; 28 December is always in the final week
Days in February28
1 January fell on aWednesday
31 December fell on aWednesday
Century17th century
Decade1680s
Chinese zodiacRooster
Easter Sunday6 April

Months of 1681

January31 days, starts Wednesday
February28 days, starts Saturday
March31 days, starts Saturday
April30 days, starts Tuesday
May31 days, starts Thursday
June30 days, starts Sunday
July31 days, starts Tuesday
August31 days, starts Friday
September30 days, starts Monday
October31 days, starts Wednesday
November30 days, starts Saturday
December31 days, starts Monday

Time references

These values depend on today’s date and change daily.

Unix timestamp at the start-9,119,865,600
Unix timestamp at the end-9,088,329,601
Years from now345 years ago
Days from today126,259 days since 1 January

The number 1681

As a number1,681
In wordsone thousand, six hundred and eighty-one
Roman numeralsMDCLXXXI

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Neighbouring years

Also reads as

#116688 (colour)

  • #116688
  • Cyan
  • Dark
  • Nearest: Steel blue

#116688 is a cyan with RGB values 17, 102, 136 and HSL 197°, 78%, 30%. It is a dark colour, so white text on it reaches 6.4:1 contrast (AA for normal text). The nearest named colour is Steel blue.

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Colour values

#116688#116688
HEX#116688
HEX (short)#168
RGBrgb(17, 102, 136)
RGB (0–1)0.0667, 0.4, 0.5333
RGB percentages6.7%, 40%, 53.3%
HSLhsl(197.1, 77.8%, 30%)
HSV / HSBhsv(197.1, 87.5%, 53.3%)
CMYK87.5%, 25%, 0%, 46.7%≈naive device-independent conversion; real print needs an ICC profile
24-bit integer1,140,360
CSS custom property--colour: #116688;

Brightness & contrast

Relative luminance0.11399WCAG 2.x, 0 is black and 1 is white
Perceived brightness91.1 of 255ITU-R BT.601 weighting
Light or darkDark
Best text colour on this backgroundWhitecontrast 6.4:1
Contrast with white6.4:1WCAG normal text: AA
Contrast with black3.28:1WCAG normal text: Fail
Greyscale equivalent#565656
Inverted#EE9977

Colour vision & accessibility

Normal visionProtanopiaDeuteranopiaTritanopia
Protanopia#55658Ano red cones; affects about 1% of men; ΔE 15.3 from the original
Deuteranopia#455A87no green cones; the most common form, about 1% of men; ΔE 16.4 from the original
Tritanopia#006F72no blue cones; rare, and affects men and women equally; ΔE 21.5 from the original
Distinguishable without hueShifts in lightness toonever rely on hue alone to carry meaning
Contrast with white, large text6.4:1WCAG large text: AAA
Contrast with black, large text3.28:1WCAG large text: AA

Named colours

Steel blue · ΔE 15.6Slate grey · ΔE 21.4Light slate grey · ΔE 23Dark slate grey · ΔE 23.6Teal · ΔE 25.9Dim grey · ΔE 28.1
Nearest named CSS colourSteel blue (#4682B4)ΔE 15.57, a distinctly different colour
Hue familycyan
CSS keyword usableNo exact keyword

Colour harmonies

base+30°+90°+120°+180°+210°+240°+270°+330°
Complementary#883311
Analogous#11886E, #112B88
Triadic#881166, #668811
Split complementary#88112B, #886E11
Tetradic#6E1188, #883311, #2B8811

Tints, shades & saturation

+40%+30%+20%+10%base-10%-20%-30%-40%
Lighter +40%#77CCEE
Lighter +30%#4ABBE8
Lighter +20%#1CAAE3
Lighter +10%#1788B5
Darker −10%#0B445B
Darker −20%#06222D
Darker −30%#000000
Darker −40%#000000
More saturated +25%#006D99
Less saturated −25%#245E75

Channel breakdown

R17
G102
B136
Red17 (6.7%)
Green102 (40%)
Blue136 (53.3%)
Hue197.14°
Saturation (HSL)77.78%
Lightness30%
Dominant channelBlue
Hex per channelR 11 · G 66 · B 88

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Every value on this page was computed from “1681” by Nerdulator’s number engine. Nothing here was retrieved from a database of answers or written by a model.