Number
685
- Positive
- Odd
- Composite
- 3 digits
685 is an odd 3-digit integer and a composite number. It has 4 divisors and a digital root of 1.
Number properties
ParityOddnot divisible by 2
SignPositive
PrimalityComposite
Absolute value685
Digit count3
Digit sum19
Digital root1repeated digit sum
PalindromicNoreads differently backwards
Happy numberNosquared-digit sums reach 1
Harshad numberNodivisible by its own digit sum
Factors & divisors
Prime factorisation5 × 137
Distinct prime factors25, 137
Number of divisors4
Sum of divisors σ(n)828
Aliquot sum143sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)544integers below n that share no factor with it
SquarefreeYesno repeated prime factor
All divisors1, 5, 137, 6854 in total
Arithmetic
Representations
Decimal685
Binary101010110110 bits
Octal1255
Hexadecimal2AD
Base 36J1
Roman numeralDCLXXXV
In wordssix hundred and eighty-five
Ordinalsix hundred and eighty-fifth
Scientific notation6.85 × 10^2
Engineering notation685
Nearest landmarks
Powers & multiples
685 to the power 2469,225
685 to the power 3321,419,125
685 to the power 4220,172,100,625
685 to the power 5150,817,888,928,125
First ten multiples685, 1,370, 2,055, 2,740, 3,425, 4,110, 4,795, 5,480, 6,165, 6,850
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 5Yes
Divisible by 6No, remainder 1
Divisible by 7No, remainder 6
Divisible by 8No, remainder 5
Divisible by 9No, remainder 1
Divisible by 10No, remainder 5
Divisible by 11No, remainder 3
Divisible by 12No, remainder 1
Divisible by 100No, remainder 85
Collatz (3n + 1) trajectory
Steps to reach 1126the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps685 → 2,056 → 1,028 → 514 → 257 → 772 → 386 → 193 → 580 → 290 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage68,500%
685% as a decimal6.85
685% of 100685
685% of 1,0006,850
As a fraction of 100685/100
Read another way
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Derived from 685
Other readings
Also reads as
#668855 (colour)
- #668855
- Green
- Dark
- Nearest: Dark olivegreen
#668855 is a green with RGB values 102, 136, 85 and HSL 100°, 23%, 43%. It is a dark colour, so black text on it reaches 5.2:1 contrast (AA for normal text). The nearest named colour is Dark olivegreen.
Colour values
#668855#668855
HEX#668855
HEX (short)#685
RGBrgb(102, 136, 85)
RGB (0–1)0.4, 0.5333, 0.3333
RGB percentages40%, 53.3%, 33.3%
HSLhsl(100, 23.1%, 43.3%)
HSV / HSBhsv(100, 37.5%, 53.3%)
CMYK25%, 0%, 37.5%, 46.7%≈naive device-independent conversion; real print needs an ICC profile
24-bit integer6,719,573
CSS custom property--colour: #668855;
Brightness & contrast
Relative luminance0.21089WCAG 2.x, 0 is black and 1 is white
Perceived brightness121.6 of 255ITU-R BT.601 weighting
Light or darkDark
Best text colour on this backgroundBlackcontrast 5.22:1
Contrast with white4.02:1WCAG normal text: Fail
Contrast with black5.22:1WCAG normal text: AA
Greyscale equivalent#7D7D7D
Inverted#9977AA
Colour vision & accessibility
Distinguishable without hueYesnever rely on hue alone to carry meaning
Contrast with white, large text4.02:1WCAG large text: AA
Contrast with black, large text5.22:1WCAG large text: AAA
Named colours
Hue familygreen
CSS keyword usableNo exact keyword
Colour harmonies
Complementary#775588
Analogous#808855, #55885E
Triadic#556688, #885566
Split complementary#5E5588, #885580
Tetradic#558088, #775588, #885E55
Tints, shades & saturation
Channel breakdown
R102
G136
B85
Red102 (40%)
Green136 (53.3%)
Blue85 (33.3%)
Hue100°
Saturation (HSL)23.08%
Lightness43.33%
Dominant channelGreen
Hex per channelR 66 · G 88 · B 55
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Harmonies
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