Recognised as Number
5
- Positive
- Odd
- Prime
- 1 digit
5 is an odd 1-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 value5
Digit count1
Digit sum5
Digit product5
Digital root5repeated digit sum
PalindromicYesreads the same backwards
Fibonacci numberYes, F(5)
Happy numberNosquared-digit sums reach 1
Harshad numberYesdivisible by its own digit sum
Armstrong numberYesdigits raised to the digit count sum to itself
Factors & divisors
Prime factorisation5
Distinct prime factors15
Number of divisors2
Sum of divisors σ(n)6
Aliquot sum1sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)4integers below n that share no factor with it
Carmichael function λ(n)4the smallest exponent with aˣ ≡ 1 for every unit coprime to n
Möbius function μ(n)−11 distinct prime factor, an odd number of them
SquarefreeYesno repeated prime factor
All divisors1, 52 in total
Arithmetic
Representations
Decimal5
Binary1013 bits
Octal5
Hexadecimal5
Base 365
Roman numeralV
In wordsfive
Ordinalfifth
Scientific notation5 × 10^0
Engineering notation5
In other bases
Ternary12base 3; the most digit-efficient integer base after e: 2 digits
Quinary10base 5; one hand: 2 digits
Septenary5base 7: 1 digit
Nonary5base 9; each digit is two ternary digits: 1 digit
Duodecimal5base 12; divides by 2, 3, 4 and 6, which is why eggs and inches come in twelves: 1 digit
Vigesimal5base 20; hands and feet, and the Mayan and Yoruba systems: 1 digit
Sexagesimal5base 60; Babylonian, and still how an hour and a circle are divided: 1 digit
Balanced ternary1TTdigits −1, 0 and +1 written T, 0 and 1; negation is swapping T and 1, so no sign is needed
Negabinary101base −2; place values alternate 1, −2, 4, −8, so every integer has exactly one form without a sign
Bit-level
00000101
Bit length3 bitsto write the magnitude
Set bits2the population count, or Hamming weight
Zero bits1within that length
Bit parityeven2 set bits, so even; not the same as the number itself being odd
Highest set bitbit 2worth 4
Lowest set bitbit 00 trailing zeros
Power of twoNo
Bytes105
Gray code111n XOR (n >> 1); successive values differ in exactly one bit
At each machine width
8-bit00000101
16-bit0000000000000101
32-bit00000000000000000000000000000101
64-bit0000000000000000000000000000000000000000000000000000000000000101
One's complement11111010at 8 bits, every bit flipped
Bits reversed10100000at 8 bits
Rotated left by 100001010at 8 bits, wrapping
Shifted left by 11010= 10, no wrap
Shifted right by 110= 2, discarding the low bit
These bits as a double2.47032823 × 10^-323≈IEEE-754 binary64 reinterpretation of the same 64 bits (subnormal)
Nearest landmarks
Powers & multiples
5 to the power 225
5 to the power 3125
5 to the power 4625
5 to the power 53,125
First ten multiples5, 10, 15, 20, 25, 30, 35, 40, 45, 50
Powers of twoBetween 2^2 (4) and 2^3 (8)
Divisibility tests
Divisible by 2No, remainder 1
Divisible by 3No, remainder 2
Divisible by 4No, remainder 1
Divisible by 5Yes
Divisible by 6No, remainder 5
Divisible by 7No, remainder 5
Divisible by 8No, remainder 5
Divisible by 9No, remainder 5
Divisible by 10No, remainder 5
Divisible by 11No, remainder 5
Divisible by 12No, remainder 5
Divisible by 100No, remainder 5
Collatz (3n + 1) trajectory
Steps to reach 15the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage500%
5% as a decimal0.05
5% of 1005
5% of 1,00050
As a fraction of 1005/100
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Derived from 5
Other readings
Also reads as
U+0035 (unicode character)
- U+0035
- 5
- Decimal digit
U+0035 is code point 53 (5), a decimal digit in the Basic Latin (ASCII) block of the Basic Multilingual Plane. It takes 1 byte in UTF-8 and 1 unit in UTF-16.
Identity
Code pointU+0035
Decimal53
Character5
General categoryDecimal digit
BlockBasic Latin (ASCII)
PlaneBasic Multilingual Planeplane 0
Official nameNot includedthe Unicode Character Database is not bundled; a stale copy would be worse than none
Encodings
UTF-8351 byte
UTF-160035a single unit
UTF-3200000035
Binary110101
Bytes in UTF-8 vs UTF-161 vs 2UTF-16 is not always smaller, even for non-Latin text
Writing it in code
HTML numeric entity5
HTML hex entity5
CSS escape\0035
JavaScript\u0035
Python\u0035
Percent-encoded (URL)%35
Things that catch people out
JavaScript string length1
Needs a surrogate pairNo
Safe in a URL unescapedYes
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