Number

25

Positive
Odd
Composite
Perfect square
2 digits

25 is an odd 2-digit integer and a composite number. It has 3 divisors and a digital root of 7.

The canonical address for this page is /25.

Number properties

ParityOddnot divisible by 2

SignPositive

PrimalityComposite

Absolute value25

Digit count2

Digit sum7

Digital root7repeated digit sum

PalindromicNoreads differently backwards

Perfect squareYes, 5²

Happy numberNosquared-digit sums reach 1

Harshad numberNodivisible by its own digit sum

Factors & divisors

Prime factorisation5^2

Distinct prime factors15

Number of divisors3

Sum of divisors σ(n)31

Aliquot sum6sum of the proper divisors

ClassificationDeficientthe aliquot sum is less than the number

Euler's totient φ(n)20integers below n that share no factor with it

SquarefreeNohas a repeated prime factor

All divisors1, 5, 253 in total

Arithmetic

Previous number24

Next number26

Double50

Half12.5

Square625

Cube15,625

Square root5exact

Cube root2.924017738≈

Negation-25

Reciprocal0.04≈

25 factorial15,511,210,043,330,985,984,000,000

Representations

Decimal25

Binary110015 bits

Octal31

Hexadecimal19

Base 36P

Roman numeralXXV

In wordstwenty-five

Ordinaltwenty-fifth

Scientific notation2.5 × 10^1

Engineering notation25

Nearest landmarks

Next prime29+4

Previous prime23−2

Distance to nearest prime2

Nearest square below25

Nearest square above36

Powers & multiples

25 to the power 2625

25 to the power 315,625

25 to the power 4390,625

25 to the power 59,765,625

First ten multiples25, 50, 75, 100, 125, 150, 175, 200, 225, 250

Powers of twoBetween 2^4 (16) and 2^5 (32)

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 4

Divisible by 8No, remainder 1

Divisible by 9No, remainder 7

Divisible by 10No, remainder 5

Divisible by 11No, remainder 3

Divisible by 12No, remainder 1

Divisible by 100No, remainder 25

Collatz (3n + 1) trajectory

Steps to reach 123the total stopping time

Highest value reached883× the starting value

Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven

First steps25 → 76 → 38 → 19 → 58 → 29 → 88 → 44 → 22 → 11 → …

Last steps… → 5 → 16 → 8 → 4 → 2 → 1

As a percentage & fraction

As a percentage2,500%

25% as a decimal0.25

25% of 10025

25% of 1,000250

As a fraction of 10025/100

Read another way

As seconds25 seconds

As bytes25 B

As a 24-bit colour#000019

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Neighbouring numbers

Derived from 25

Nearby primes

#000025 (colour)

#000025
Blue
Dark
Nearest: Black

#000025 is a blue with RGB values 0, 0, 37 and HSL 240°, 100%, 7%. It is a dark colour, so white text on it reaches 20.5:1 contrast (AAA for normal text). The nearest named colour is Black.

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Colour values

#000025#000025

HEX#000025

RGBrgb(0, 0, 37)

RGB (0–1)0, 0, 0.1451

RGB percentages0%, 0%, 14.5%

HSLhsl(240, 100%, 7.3%)

HSV / HSBhsv(240, 100%, 14.5%)

CMYK100%, 100%, 0%, 85.5%≈naive device-independent conversion; real print needs an ICC profile

24-bit integer37

CSS custom property--colour: #000025;

Brightness & contrast

Relative luminance0.00134WCAG 2.x, 0 is black and 1 is white

Perceived brightness12.5 of 255ITU-R BT.601 weighting

Light or darkDark

Best text colour on this backgroundWhitecontrast 20.45:1

Contrast with white20.45:1WCAG normal text: AAA

Contrast with black1.03:1WCAG normal text: Fail

Greyscale equivalent#030303

Inverted#FFFFDA

Colour vision & accessibility

Normal vision Protanopia Deuteranopia Tritanopia

Protanopia#000626no red cones; affects about 1% of men; ΔE 2.6 from the original

Deuteranopia#000324no green cones; the most common form, about 1% of men; ΔE 2.3 from the original

Tritanopia#000911no blue cones; rare, and affects men and women equally; ΔE 19 from the original

Distinguishable without hueYesnever rely on hue alone to carry meaning

Contrast with white, large text20.45:1WCAG large text: AAA

Contrast with black, large text1.03:1WCAG large text: Fail

Named colours

Black · ΔE 22.6 Midnight blue · ΔE 39.7 Dark slate grey · ΔE 40.1 Dark slateblue · ΔE 40.4 Dim grey · ΔE 48.7 Rebecca purple · ΔE 53.7

Nearest named CSS colourBlack (#000000)ΔE 22.57, a distinctly different colour

Hue familyblue

CSS keyword usableNo exact keyword

Colour harmonies

base +30°+90°+120°+180°+210°+240°+270°+330°

Complementary#252500

Analogous#001325, #130025

Triadic#250000, #002500

Split complementary#251300, #132500

Tetradic#250013, #252500, #002513

Tints, shades & saturation

+40%+30%+20%+10%base -10%-20%-30%-40%

Lighter +40%#0000F1

Lighter +30%#0000BE

Lighter +20%#00008B

Lighter +10%#000058

Darker −10%#000000

Darker −20%#000000

Darker −30%#000000

Darker −40%#000000

More saturated +25%#000025

Less saturated −25%#050520

Channel breakdown

B37

Red0 (0%)

Green0 (0%)

Blue37 (14.5%)

Hue240°

Saturation (HSL)100%

Lightness7.25%

Dominant channelBlue

Hex per channelR 00 · G 00 · B 25

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25

Number properties

Factors & divisors

Arithmetic

Representations

Nearest landmarks

Powers & multiples

Divisibility tests

Collatz (3n + 1) trajectory

As a percentage & fraction

Read another way

Keep nerding

Neighbouring numbers

Derived from 25

Nearby primes

Other readings

#000025 (colour)

Colour values

Brightness & contrast

Colour vision & accessibility

Named colours

Colour harmonies

Tints, shades & saturation

Channel breakdown

Keep nerding

Harmonies

Lighter and darker

Similar named colours

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