Number
311
- Positive
- Odd
- Prime
- 3 digits
311 is an odd 3-digit integer and a prime number. It has 2 divisors and a digital root of 5.
Number properties
ParityOddnot divisible by 2
SignPositive
PrimalityPrime
Absolute value311
Digit count3
Digit sum5
Digital root5repeated digit sum
PalindromicNoreads differently backwards
Happy numberNosquared-digit sums reach 1
Harshad numberNodivisible by its own digit sum
Factors & divisors
Prime factorisation311
Distinct prime factors1311
Number of divisors2
Sum of divisors σ(n)312
Aliquot sum1sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)310integers below n that share no factor with it
SquarefreeYesno repeated prime factor
All divisors1, 3112 in total
Arithmetic
Representations
Decimal311
Binary1001101119 bits
Octal467
Hexadecimal137
Base 368N
Roman numeralCCCXI
In wordsthree hundred and eleven
Ordinalthree hundred and eleventh
Scientific notation3.11 × 10^2
Engineering notation311
Nearest landmarks
Powers & multiples
311 to the power 296,721
311 to the power 330,080,231
311 to the power 49,354,951,841
311 to the power 52,909,390,022,551
First ten multiples311, 622, 933, 1,244, 1,555, 1,866, 2,177, 2,488, 2,799, 3,110
Powers of twoBetween 2^8 (256) and 2^9 (512)
Divisibility tests
Divisible by 2No, remainder 1
Divisible by 3No, remainder 2
Divisible by 4No, remainder 3
Divisible by 5No, remainder 1
Divisible by 6No, remainder 5
Divisible by 7No, remainder 3
Divisible by 8No, remainder 7
Divisible by 9No, remainder 5
Divisible by 10No, remainder 1
Divisible by 11No, remainder 3
Divisible by 12No, remainder 11
Divisible by 100No, remainder 11
Collatz (3n + 1) trajectory
Steps to reach 186the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps311 → 934 → 467 → 1,402 → 701 → 2,104 → 1,052 → 526 → 263 → 790 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage31,100%
311% as a decimal3.11
311% of 100311
311% of 1,0003,110
As a fraction of 100311/100
Read another way
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Derived from 311
Other readings
Also reads as
#331111 (colour)
- #331111
- Red
- Dark
- Nearest: Black
#331111 is a red with RGB values 51, 17, 17 and HSL 0°, 50%, 13%. It is a dark colour, so white text on it reaches 17.1:1 contrast (AAA for normal text). The nearest named colour is Black.
Colour values
#331111#331111
HEX#331111
HEX (short)#311
RGBrgb(51, 17, 17)
RGB (0–1)0.2, 0.0667, 0.0667
RGB percentages20%, 6.7%, 6.7%
HSLhsl(0, 50%, 13.3%)
HSV / HSBhsv(0, 66.7%, 20%)
CMYK0%, 66.7%, 66.7%, 80%≈naive device-independent conversion; real print needs an ICC profile
24-bit integer3,346,705
CSS custom property--colour: #331111;
Brightness & contrast
Relative luminance0.01145WCAG 2.x, 0 is black and 1 is white
Perceived brightness31.3 of 255ITU-R BT.601 weighting
Light or darkDark
Best text colour on this backgroundWhitecontrast 17.09:1
Contrast with white17.09:1WCAG normal text: AAA
Contrast with black1.23:1WCAG normal text: Fail
Greyscale equivalent#181818
Inverted#CCEEEE
Colour vision & accessibility
Distinguishable without hueYesnever rely on hue alone to carry meaning
Contrast with white, large text17.09:1WCAG large text: AAA
Contrast with black, large text1.23:1WCAG large text: Fail
Named colours
Hue familyred
CSS keyword usableNo exact keyword
Colour harmonies
Complementary#113333
Analogous#331122, #332211
Triadic#113311, #111133
Split complementary#113322, #112233
Tetradic#223311, #113333, #221133
Tints, shades & saturation
Channel breakdown
R51
G17
B17
Red51 (20%)
Green17 (6.7%)
Blue17 (6.7%)
Hue0°
Saturation (HSL)50%
Lightness13.33%
Dominant channelRed
Hex per channelR 33 · G 11 · B 11
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Harmonies
Similar named colours
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