Number
400
- Positive
- Even
- Composite
- Perfect square
- 3 digits
400 is an even 3-digit integer and a composite number. It has 15 divisors and a digital root of 4.
The canonical address for this page is /400.
Number properties
ParityEvendivisible by 2
SignPositive
PrimalityComposite
Absolute value400
Digit count3
Digit sum4
Digital root4repeated digit sum
PalindromicNoreads differently backwards
Perfect squareYes, 20²
Happy numberNosquared-digit sums reach 1
Harshad numberYesdivisible by its own digit sum
Factors & divisors
Prime factorisation2^4 × 5^2
Distinct prime factors22, 5
Number of divisors15
Sum of divisors σ(n)961
Aliquot sum561sum of the proper divisors
ClassificationAbundantthe aliquot sum exceeds the number
Euler's totient φ(n)160integers below n that share no factor with it
SquarefreeNohas a repeated prime factor
All divisors1, 2, 4, 5, 8, 10, 16, 20, 25, 40, 50, 80, 100, 200, 40015 in total
Arithmetic
Representations
Decimal400
Binary1100100009 bits
Octal620
Hexadecimal190
Base 36B4
Roman numeralCD
In wordsfour hundred
Ordinalfour hundredth
Scientific notation4 × 10^2
Engineering notation400
Nearest landmarks
Powers & multiples
400 to the power 2160,000
400 to the power 364,000,000
400 to the power 425,600,000,000
400 to the power 510,240,000,000,000
First ten multiples400, 800, 1,200, 1,600, 2,000, 2,400, 2,800, 3,200, 3,600, 4,000
Powers of twoBetween 2^8 (256) and 2^9 (512)
Divisibility tests
Divisible by 2Yes
Divisible by 3No, remainder 1
Divisible by 4Yes
Divisible by 5Yes
Divisible by 6No, remainder 4
Divisible by 7No, remainder 1
Divisible by 8Yes
Divisible by 9No, remainder 4
Divisible by 10Yes
Divisible by 11No, remainder 4
Divisible by 12No, remainder 4
Divisible by 100Yes
Collatz (3n + 1) trajectory
Steps to reach 127the total stopping time
Highest value reached400
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps400 → 200 → 100 → 50 → 25 → 76 → 38 → 19 → 58 → 29 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage40,000%
400% as a decimal4
400% of 100400
400% of 1,0004,000
As a fraction of 100400/100
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Derived from 400
Other readings
Also reads as
#000400 (colour)
- #000400
- Green
- Dark
- Nearest: Black
#000400 is a green with RGB values 0, 4, 0 and HSL 120°, 100%, 1%. It is a dark colour, so white text on it reaches 20.6:1 contrast (AAA for normal text). The nearest named colour is Black.
Colour values
#000400#000400
HEX#000400
RGBrgb(0, 4, 0)
RGB (0–1)0, 0.0157, 0
RGB percentages0%, 1.6%, 0%
HSLhsl(120, 100%, 0.8%)
HSV / HSBhsv(120, 100%, 1.6%)
CMYK100%, 0%, 100%, 98.4%≈naive device-independent conversion; real print needs an ICC profile
24-bit integer1,024
CSS custom property--colour: #000400;
Brightness & contrast
Relative luminance0.00087WCAG 2.x, 0 is black and 1 is white
Perceived brightness3.1 of 255ITU-R BT.601 weighting
Light or darkDark
Best text colour on this backgroundWhitecontrast 20.64:1
Contrast with white20.64:1WCAG normal text: AAA
Contrast with black1.02:1WCAG normal text: Fail
Greyscale equivalent#030303
Inverted#FFFBFF
Colour vision & accessibility
Distinguishable without hueYesnever rely on hue alone to carry meaning
Contrast with white, large text20.64:1WCAG large text: AAA
Contrast with black, large text1.02:1WCAG large text: Fail
Named colours
Hue familygreen
CSS keyword usableNo exact keyword
Colour harmonies
Complementary#040004
Analogous#020400, #000402
Triadic#000004, #040000
Split complementary#020004, #040002
Tetradic#000204, #040004, #040200
Tints, shades & saturation
Channel breakdown
R0
G4
B0
Red0 (0%)
Green4 (1.6%)
Blue0 (0%)
Hue120°
Saturation (HSL)100%
Lightness0.78%
Dominant channelGreen
Hex per channelR 00 · G 04 · B 00
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