Number
401
- Positive
- Odd
- Prime
- 3 digits
401 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 value401
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 factorisation401
Distinct prime factors1401
Number of divisors2
Sum of divisors σ(n)402
Aliquot sum1sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)400integers below n that share no factor with it
SquarefreeYesno repeated prime factor
All divisors1, 4012 in total
Arithmetic
Representations
Decimal401
Binary1100100019 bits
Octal621
Hexadecimal191
Base 36B5
Roman numeralCDI
In wordsfour hundred and one
Ordinalfour hundred and first
Scientific notation4.01 × 10^2
Engineering notation401
Nearest landmarks
Powers & multiples
401 to the power 2160,801
401 to the power 364,481,201
401 to the power 425,856,961,601
401 to the power 510,368,641,602,001
First ten multiples401, 802, 1,203, 1,604, 2,005, 2,406, 2,807, 3,208, 3,609, 4,010
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 1
Divisible by 5No, remainder 1
Divisible by 6No, remainder 5
Divisible by 7No, remainder 2
Divisible by 8No, remainder 1
Divisible by 9No, remainder 5
Divisible by 10No, remainder 1
Divisible by 11No, remainder 5
Divisible by 12No, remainder 5
Divisible by 100No, remainder 1
Collatz (3n + 1) trajectory
Steps to reach 119the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps401 → 1,204 → 602 → 301 → 904 → 452 → 226 → 113 → 340 → 170 → …
Last steps… → 32 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage40,100%
401% as a decimal4.01
401% of 100401
401% of 1,0004,010
As a fraction of 100401/100
Read another way
Keep nerding
Every link below is a page Nerdulator can generate from what it already knows about this value.
Derived from 401
Other readings
Also reads as
#440011 (colour)
- #440011
- Red
- Dark
- Nearest: Black
#440011 is a red with RGB values 68, 0, 17 and HSL 345°, 100%, 13%. It is a dark colour, so white text on it reaches 16.7:1 contrast (AAA for normal text). The nearest named colour is Black.
Colour values
#440011#440011
HEX#440011
HEX (short)#401
RGBrgb(68, 0, 17)
RGB (0–1)0.2667, 0, 0.0667
RGB percentages26.7%, 0%, 6.7%
HSLhsl(345, 100%, 13.3%)
HSV / HSBhsv(345, 100%, 26.7%)
CMYK0%, 100%, 75%, 73.3%≈naive device-independent conversion; real print needs an ICC profile
24-bit integer4,456,465
CSS custom property--colour: #440011;
Brightness & contrast
Relative luminance0.01269WCAG 2.x, 0 is black and 1 is white
Perceived brightness37.6 of 255ITU-R BT.601 weighting
Light or darkDark
Best text colour on this backgroundWhitecontrast 16.75:1
Contrast with white16.75:1WCAG normal text: AAA
Contrast with black1.25:1WCAG normal text: Fail
Greyscale equivalent#101010
Inverted#BBFFEE
Colour vision & accessibility
Distinguishable without hueShifts in lightness toonever rely on hue alone to carry meaning
Contrast with white, large text16.75:1WCAG large text: AAA
Contrast with black, large text1.25:1WCAG large text: Fail
Named colours
Hue familyred
CSS keyword usableNo exact keyword
Colour harmonies
Complementary#004433
Analogous#440033, #441100
Triadic#114400, #001144
Split complementary#004411, #003344
Tetradic#334400, #004433, #110044
Tints, shades & saturation
Channel breakdown
R68
G0
B17
Red68 (26.7%)
Green0 (0%)
Blue17 (6.7%)
Hue345°
Saturation (HSL)100%
Lightness13.33%
Dominant channelRed
Hex per channelR 44 · G 00 · B 11
Keep nerding
Every link below is a page Nerdulator can generate from what it already knows about this value.
Also reads as
HTTP 401 Unauthorized (http status)
- 401 Unauthorized
- Client error
- RFC 9110
HTTP 401 Unauthorized is a client error response: authentication is required and has failed or not been supplied. It is defined in RFC 9110, and the request was malformed or cannot be fulfilled as sent.
What it means
Status code401
Reason phraseUnauthorizedadvisory only; clients must not depend on the wording
Class4xx Client error
MeaningAuthentication is required and has failed or not been supplied
Defined inRFC 9110
Cacheable by defaultNoonly cacheable if the response says so explicitly
How clients behave
Indicates an errorYes
Whose faultThe request
Body expectedUsually
Safe to retry automaticallyNo
The 4xx class
Class meaningThe request was malformed or cannot be fulfilled as sent
Codes in this class29
Lowest in class400
Highest in class451
Keep nerding
Every link below is a page Nerdulator can generate from what it already knows about this value.
Other 4xx codes
Commonly confused with
Read another way
Nerdulate something else
Nothing in mind? Surprise me · today’s page