Number
128
- Positive
- Even
- Composite
- 3 digits
128 is an even 3-digit integer and a composite number. It has 8 divisors and a digital root of 2.
Number properties
ParityEvendivisible by 2
SignPositive
PrimalityComposite
Absolute value128
Digit count3
Digit sum11
Digital root2repeated digit sum
PalindromicNoreads differently backwards
Happy numberNosquared-digit sums reach 1
Harshad numberNodivisible by its own digit sum
Factors & divisors
Prime factorisation2^7
Distinct prime factors12
Number of divisors8
Sum of divisors σ(n)255
Aliquot sum127sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)64integers below n that share no factor with it
SquarefreeNohas a repeated prime factor
All divisors1, 2, 4, 8, 16, 32, 64, 1288 in total
Arithmetic
Representations
Decimal128
Binary100000008 bits
Octal200
Hexadecimal80
Base 363K
Roman numeralCXXVIII
In wordsone hundred and twenty-eight
Ordinalone hundred and twenty-eighth
Scientific notation1.28 × 10^2
Engineering notation128
Nearest landmarks
Powers & multiples
128 to the power 216,384
128 to the power 32,097,152
128 to the power 4268,435,456
128 to the power 534,359,738,368
First ten multiples128, 256, 384, 512, 640, 768, 896, 1,024, 1,152, 1,280
Powers of twoExactly 2^7
Divisibility tests
Divisible by 2Yes
Divisible by 3No, remainder 2
Divisible by 4Yes
Divisible by 5No, remainder 3
Divisible by 6No, remainder 2
Divisible by 7No, remainder 2
Divisible by 8Yes
Divisible by 9No, remainder 2
Divisible by 10No, remainder 8
Divisible by 11No, remainder 7
Divisible by 12No, remainder 8
Divisible by 100No, remainder 28
Collatz (3n + 1) trajectory
Steps to reach 17the total stopping time
Highest value reached128
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps128 → 64 → 32 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage12,800%
128% as a decimal1.28
128% of 100128
128% of 1,0001,280
As a fraction of 100128/100
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Derived from 128
Other readings
Also reads as
#112288 (colour)
- #112288
- Blue
- Dark
- Nearest: Midnight blue
#112288 is a blue with RGB values 17, 34, 136 and HSL 231°, 78%, 30%. It is a dark colour, so white text on it reaches 13.1:1 contrast (AAA for normal text). The nearest named colour is Midnight blue.
Colour values
#112288#112288
HEX#112288
HEX (short)#128
RGBrgb(17, 34, 136)
RGB (0–1)0.0667, 0.1333, 0.5333
RGB percentages6.7%, 13.3%, 53.3%
HSLhsl(231.4, 77.8%, 30%)
HSV / HSBhsv(231.4, 87.5%, 53.3%)
CMYK87.5%, 75%, 0%, 46.7%≈naive device-independent conversion; real print needs an ICC profile
24-bit integer1,122,952
CSS custom property--colour: #112288;
Brightness & contrast
Relative luminance0.03041WCAG 2.x, 0 is black and 1 is white
Perceived brightness53.6 of 255ITU-R BT.601 weighting
Light or darkDark
Best text colour on this backgroundWhitecontrast 13.06:1
Contrast with white13.06:1WCAG normal text: AAA
Contrast with black1.61:1WCAG normal text: Fail
Greyscale equivalent#262626
Inverted#EEDD77
Colour vision & accessibility
Distinguishable without hueShifts in lightness toonever rely on hue alone to carry meaning
Contrast with white, large text13.06:1WCAG large text: AAA
Contrast with black, large text1.61:1WCAG large text: Fail
Named colours
Hue familyblue
CSS keyword usableNo exact keyword
Colour harmonies
Complementary#887711
Analogous#115D88, #3C1188
Triadic#881122, #228811
Split complementary#883C11, #5D8811
Tetradic#88115D, #887711, #11883C
Tints, shades & saturation
Channel breakdown
R17
G34
B136
Red17 (6.7%)
Green34 (13.3%)
Blue136 (53.3%)
Hue231.43°
Saturation (HSL)77.78%
Lightness30%
Dominant channelBlue
Hex per channelR 11 · G 22 · B 88
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Harmonies
Similar named colours
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