Number
1,021
- Positive
- Odd
- Prime
- 4 digits
1,021 is an odd 4-digit integer and a prime number. It has 2 divisors and a digital root of 4.
Number properties
ParityOddnot divisible by 2
SignPositive
PrimalityPrime
Absolute value1,021
Digit count4
Digit sum4
Digital root4repeated digit sum
PalindromicNoreads differently backwards
Happy numberNosquared-digit sums reach 1
Harshad numberNodivisible by its own digit sum
Factors & divisors
Prime factorisation1,021
Distinct prime factors11,021
Number of divisors2
Sum of divisors σ(n)1,022
Aliquot sum1sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)1,020integers below n that share no factor with it
SquarefreeYesno repeated prime factor
All divisors1, 1,0212 in total
Arithmetic
Representations
Decimal1,021
Binary111111110110 bits
Octal1775
Hexadecimal3FD
Base 36SD
Roman numeralMXXI
In wordsone thousand and twenty-one
Ordinalone thousand and twenty-first
Scientific notation1.021 × 10^3
Engineering notation1.021 × 10^3
Nearest landmarks
Powers & multiples
1,021 to the power 21,042,441
1,021 to the power 31,064,332,261
1,021 to the power 41,086,683,238,481
1,021 to the power 51,109,503,586,489,101
First ten multiples1,021, 2,042, 3,063, 4,084, 5,105, 6,126, 7,147, 8,168, 9,189, 10,210
Powers of twoBetween 2^9 (512) and 2^10 (1,024)
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 6
Divisible by 8No, remainder 5
Divisible by 9No, remainder 4
Divisible by 10No, remainder 1
Divisible by 11No, remainder 9
Divisible by 12No, remainder 1
Divisible by 100No, remainder 21
Collatz (3n + 1) trajectory
Steps to reach 149the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps1,021 → 3,064 → 1,532 → 766 → 383 → 1,150 → 575 → 1,726 → 863 → 2,590 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage102,100%
1,021% as a decimal10.21
1,021% of 1001,021
1,021% of 1,00010,210
As a fraction of 1001,021/100
Read another way
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Derived from 1,021
Also reads as
1021 (year)
- Common year
- 365 days
- 11th century
- Rooster
1021 was a common year of 365 days. It began on a Monday and ended on a Monday. Easter Sunday fell on 8 April.
Structure of the year
Months of 1021
January31 days, starts Monday
February28 days, starts Thursday
September30 days, starts Saturday
October31 days, starts Monday
November30 days, starts Thursday
December31 days, starts Saturday
Time references
These values depend on today’s date and change daily.
Unix timestamp at the start-29,947,536,000
Unix timestamp at the end-29,916,000,001
Years from now1,005 years ago
Days from today367,320 days since 1 January
The number 1021
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Also reads as
#110022 (colour)
- #110022
- Violet
- Dark
- Nearest: Black
#110022 is a violet with RGB values 17, 0, 34 and HSL 270°, 100%, 7%. It is a dark colour, so white text on it reaches 20.1:1 contrast (AAA for normal text). The nearest named colour is Black.
Colour values
#110022#110022
HEX#110022
HEX (short)#102
RGBrgb(17, 0, 34)
RGB (0–1)0.0667, 0, 0.1333
RGB percentages6.7%, 0%, 13.3%
HSLhsl(270, 100%, 6.7%)
HSV / HSBhsv(270, 100%, 13.3%)
CMYK50%, 100%, 0%, 86.7%≈naive device-independent conversion; real print needs an ICC profile
24-bit integer1,114,146
CSS custom property--colour: #110022;
Brightness & contrast
Relative luminance0.00235WCAG 2.x, 0 is black and 1 is white
Perceived brightness14.8 of 255ITU-R BT.601 weighting
Light or darkDark
Best text colour on this backgroundWhitecontrast 20.06:1
Contrast with white20.06:1WCAG normal text: AAA
Contrast with black1.05:1WCAG normal text: Fail
Greyscale equivalent#060606
Inverted#EEFFDD
Colour vision & accessibility
Distinguishable without hueYesnever rely on hue alone to carry meaning
Contrast with white, large text20.06:1WCAG large text: AAA
Contrast with black, large text1.05:1WCAG large text: Fail
Named colours
Hue familyviolet
CSS keyword usableNo exact keyword
Colour harmonies
Complementary#112200
Analogous#000022, #220022
Triadic#221100, #002211
Split complementary#222200, #002200
Tetradic#220000, #112200, #002222
Tints, shades & saturation
Channel breakdown
R17
G0
B34
Red17 (6.7%)
Green0 (0%)
Blue34 (13.3%)
Hue270°
Saturation (HSL)100%
Lightness6.67%
Dominant channelBlue
Hex per channelR 11 · G 00 · B 22
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Harmonies
Similar named colours
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