Number
231
- Positive
- Odd
- Composite
- 3 digits
231 is an odd 3-digit integer and a composite number. It has 8 divisors and a digital root of 6.
Number properties
ParityOddnot divisible by 2
SignPositive
PrimalityComposite
Absolute value231
Digit count3
Digit sum6
Digital root6repeated digit sum
PalindromicNoreads differently backwards
Triangular numberYes, the 21st triangular number
Happy numberNosquared-digit sums reach 1
Harshad numberNodivisible by its own digit sum
Factors & divisors
Prime factorisation3 × 7 × 11
Distinct prime factors33, 7, 11
Number of divisors8
Sum of divisors σ(n)384
Aliquot sum153sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)120integers below n that share no factor with it
SquarefreeYesno repeated prime factor
All divisors1, 3, 7, 11, 21, 33, 77, 2318 in total
Arithmetic
Representations
Decimal231
Binary111001118 bits
Octal347
HexadecimalE7
Base 366F
Roman numeralCCXXXI
In wordstwo hundred and thirty-one
Ordinaltwo hundred and thirty-first
Scientific notation2.31 × 10^2
Engineering notation231
Nearest landmarks
Powers & multiples
231 to the power 253,361
231 to the power 312,326,391
231 to the power 42,847,396,321
231 to the power 5657,748,550,151
First ten multiples231, 462, 693, 924, 1,155, 1,386, 1,617, 1,848, 2,079, 2,310
Powers of twoBetween 2^7 (128) and 2^8 (256)
Divisibility tests
Divisible by 2No, remainder 1
Divisible by 3Yes
Divisible by 4No, remainder 3
Divisible by 5No, remainder 1
Divisible by 6No, remainder 3
Divisible by 7Yes
Divisible by 8No, remainder 7
Divisible by 9No, remainder 6
Divisible by 10No, remainder 1
Divisible by 11Yes
Divisible by 12No, remainder 3
Divisible by 100No, remainder 31
Collatz (3n + 1) trajectory
Steps to reach 1127the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps231 → 694 → 347 → 1,042 → 521 → 1,564 → 782 → 391 → 1,174 → 587 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage23,100%
231% as a decimal2.31
231% of 100231
231% of 1,0002,310
As a fraction of 100231/100
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Derived from 231
Other readings
Also reads as
#223311 (colour)
- #223311
- Green
- Dark
- Nearest: Dark slate grey
#223311 is a green with RGB values 34, 51, 17 and HSL 90°, 50%, 13%. It is a dark colour, so white text on it reaches 13.6:1 contrast (AAA for normal text). The nearest named colour is Dark slate grey.
Colour values
#223311#223311
HEX#223311
HEX (short)#231
RGBrgb(34, 51, 17)
RGB (0–1)0.1333, 0.2, 0.0667
RGB percentages13.3%, 20%, 6.7%
HSLhsl(90, 50%, 13.3%)
HSV / HSBhsv(90, 66.7%, 20%)
CMYK33.3%, 0%, 66.7%, 80%≈naive device-independent conversion; real print needs an ICC profile
24-bit integer2,241,297
CSS custom property--colour: #223311;
Brightness & contrast
Relative luminance0.02748WCAG 2.x, 0 is black and 1 is white
Perceived brightness43.7 of 255ITU-R BT.601 weighting
Light or darkDark
Best text colour on this backgroundWhitecontrast 13.55:1
Contrast with white13.55:1WCAG normal text: AAA
Contrast with black1.55:1WCAG normal text: Fail
Greyscale equivalent#2D2D2D
Inverted#DDCCEE
Colour vision & accessibility
Distinguishable without hueYesnever rely on hue alone to carry meaning
Contrast with white, large text13.55:1WCAG large text: AAA
Contrast with black, large text1.55:1WCAG large text: Fail
Named colours
Hue familygreen
CSS keyword usableNo exact keyword
Colour harmonies
Complementary#221133
Analogous#333311, #113311
Triadic#112233, #331122
Split complementary#111133, #331133
Tetradic#113333, #221133, #331111
Tints, shades & saturation
Channel breakdown
R34
G51
B17
Red34 (13.3%)
Green51 (20%)
Blue17 (6.7%)
Hue90°
Saturation (HSL)50%
Lightness13.33%
Dominant channelGreen
Hex per channelR 22 · G 33 · B 11
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Harmonies
Similar named colours
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