Recognised as Number
-13
- Negative
- Odd
- 2 digits
-13 is an odd 2-digit integer and the negative of 13. It has 2 divisors and a digital root of 4.
Number properties
ParityOddnot divisible by 2
SignNegative
Absolute value13
Digit count2
Digit sum4
Digit product3
Multiplicative persistence1times the digit product can be taken before one digit is left
Digital root4repeated digit sum
PalindromicNoreads differently backwards
Factors & divisors
Prime factorisation−1 × 13
Distinct prime factors113
Number of divisors2
Sum of divisors σ(n)14
SquarefreeYesno repeated prime factor
All divisors1, 132 in total
Arithmetic
Representations
Decimal-13
Binary11014 bits
Octal15
HexadecimalD
Base 36D
In wordsminus thirteen
Ordinalminus thirteenth
Scientific notation-1.3 × 10^1
Engineering notation-13
In other bases
Ternary111base 3; the most digit-efficient integer base after e: 3 digits
Quinary23base 5; one hand: 2 digits
Septenary16base 7: 2 digits
Nonary14base 9; each digit is two ternary digits: 2 digits
Duodecimal11base 12; divides by 2, 3, 4 and 6, which is why eggs and inches come in twelves: 2 digits
Vigesimaldbase 20; hands and feet, and the Mayan and Yoruba systems: 1 digit
Sexagesimal13base 60; Babylonian, and still how an hour and a circle are divided: 1 digit
Balanced ternaryTTTdigits −1, 0 and +1 written T, 0 and 1; negation is swapping T and 1, so no sign is needed
Negabinary110111base −2; place values alternate 1, −2, 4, −8, so every integer has exactly one form without a sign
Bit-level
11110011
Bit length4 bitsto write the magnitude
Set bits3the population count, or Hamming weight
Zero bits1within that length
Bit parityodd3 set bits, so odd; not the same as the number itself being odd
Highest set bitbit 3worth 8
Lowest set bitbit 00 trailing zeros
Power of twoNo
Bytes10d
Gray code1011n XOR (n >> 1); successive values differ in exactly one bit
At each machine width
8-bit11110011two's complement
16-bit1111111111110011two's complement
32-bit11111111111111111111111111110011two's complement
64-bit1111111111111111111111111111111111111111111111111111111111110011two's complement
One's complement00001100at 8 bits, every bit flipped
Bits reversed11001111at 8 bits
Rotated left by 111100111at 8 bits, wrapping
Shifted left by 1-11010= -26, no wrap
Shifted right by 1-111= -6, discarding the low bit
These bits as a double6.4228534 × 10^-323≈IEEE-754 binary64 reinterpretation of the same 64 bits (subnormal)
Powers & multiples
-13 to the power 2169
-13 to the power 3-2,197
-13 to the power 428,561
-13 to the power 5-371,293
First ten multiples-13, -26, -39, -52, -65, -78, -91, -104, -117, -130
Powers of twoBetween 2^3 (8) and 2^4 (16)
Divisibility tests
Divisible by 2No, remainder 1
Divisible by 3No, remainder 1
Divisible by 4No, remainder 1
Divisible by 5No, remainder 3
Divisible by 6No, remainder 1
Divisible by 7No, remainder 6
Divisible by 8No, remainder 5
Divisible by 9No, remainder 4
Divisible by 10No, remainder 3
Divisible by 11No, remainder 2
Divisible by 12No, remainder 1
Divisible by 100No, remainder 13
As a percentage & fraction
As a percentage-1,300%
-13% as a decimal-0.13
-13% of 100-13
-13% of 1,000-130
As a fraction of 100-13/100
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