Number
990
- Positive
- Even
- Composite
- 3 digits
990 is an even 3-digit integer and a composite number. It has 24 divisors and a digital root of 9.
Number properties
ParityEvendivisible by 2
SignPositive
PrimalityComposite
Absolute value990
Digit count3
Digit sum18
Digital root9repeated digit sum
PalindromicNoreads differently backwards
Triangular numberYes, the 44th triangular number
Happy numberNosquared-digit sums reach 1
Harshad numberYesdivisible by its own digit sum
Factors & divisors
Prime factorisation2 × 3^2 × 5 × 11
Distinct prime factors42, 3, 5, 11
Number of divisors24
Sum of divisors σ(n)2,808
Aliquot sum1,818sum of the proper divisors
ClassificationAbundantthe aliquot sum exceeds the number
Euler's totient φ(n)240integers below n that share no factor with it
SquarefreeNohas a repeated prime factor
All divisors1, 2, 3, 5, 6, 9, 10, 11, 15, 18, 22, 30, 33, 45, 55, 66, 90, 99, 110, 165, 198, 330, 495, 99024 in total
Arithmetic
Representations
Decimal990
Binary111101111010 bits
Octal1736
Hexadecimal3DE
Base 36RI
Roman numeralCMXC
In wordsnine hundred and ninety
Ordinalnine hundred and ninetieth
Scientific notation9.9 × 10^2
Engineering notation990
Nearest landmarks
Powers & multiples
990 to the power 2980,100
990 to the power 3970,299,000
990 to the power 4960,596,010,000
990 to the power 5950,990,049,900,000
First ten multiples990, 1,980, 2,970, 3,960, 4,950, 5,940, 6,930, 7,920, 8,910, 9,900
Powers of twoBetween 2^9 (512) and 2^10 (1,024)
Divisibility tests
Divisible by 2Yes
Divisible by 3Yes
Divisible by 4No, remainder 2
Divisible by 5Yes
Divisible by 6Yes
Divisible by 7No, remainder 3
Divisible by 8No, remainder 6
Divisible by 9Yes
Divisible by 10Yes
Divisible by 11Yes
Divisible by 12No, remainder 6
Divisible by 100No, remainder 90
Collatz (3n + 1) trajectory
Steps to reach 198the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps990 → 495 → 1,486 → 743 → 2,230 → 1,115 → 3,346 → 1,673 → 5,020 → 2,510 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage99,000%
990% as a decimal9.9
990% of 100990
990% of 1,0009,900
As a fraction of 100990/100
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Derived from 990
Other readings
Also reads as
#999900 (colour)
- #999900
- Yellow
- Dark
- Nearest: Olive
#999900 is a yellow with RGB values 153, 153, 0 and HSL 60°, 100%, 30%. It is a dark colour, so black text on it reaches 6.9:1 contrast (AA for normal text). The nearest named colour is Olive.
Colour values
#999900#999900
HEX#999900
HEX (short)#990
RGBrgb(153, 153, 0)
RGB (0–1)0.6, 0.6, 0
RGB percentages60%, 60%, 0%
HSLhsl(60, 100%, 30%)
HSV / HSBhsv(60, 100%, 60%)
CMYK0%, 0%, 100%, 40%≈naive device-independent conversion; real print needs an ICC profile
24-bit integer10,066,176
CSS custom property--colour: #999900;
Brightness & contrast
Relative luminance0.29555WCAG 2.x, 0 is black and 1 is white
Perceived brightness144 of 255ITU-R BT.601 weighting
Light or darkDark
Best text colour on this backgroundBlackcontrast 6.91:1
Contrast with white3.04:1WCAG normal text: Fail
Contrast with black6.91:1WCAG normal text: AA
Greyscale equivalent#8E8E8E
Inverted#6666FF
Colour vision & accessibility
Distinguishable without hueYesnever rely on hue alone to carry meaning
Contrast with white, large text3.04:1WCAG large text: AA
Contrast with black, large text6.91:1WCAG large text: AAA
Named colours
Hue familyyellow
CSS keyword usableNo exact keyword
Colour harmonies
Complementary#000099
Analogous#994D00, #4D9900
Triadic#009999, #990099
Split complementary#004D99, #4D0099
Tetradic#00994D, #000099, #99004D
Tints, shades & saturation
Channel breakdown
R153
G153
B0
Red153 (60%)
Green153 (60%)
Blue0 (0%)
Hue60°
Saturation (HSL)100%
Lightness30%
Dominant channelRed and Green
Hex per channelR 99 · G 99 · B 00
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