Properties of the Number -31

Thirty-One

Basics

Value: -32 → -31 → -30

Parity: odd

Prime: No

Previous Prime:

Next Prime: 1

Digit Sum: 4

Digital Root: 4

Palindrome: No

Factorization: 31

Divisors: 1, 31

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: -11111

Octal: -37

Duodecimal: -27

Hexadecimal: -1f

Square: 961

Square Root: 5.5677643628300215

Classification

Fibonacci: No

Bell Number: No

Factorial Number: No

Regular Number: No

Perfect Number: No

Special

Kaprekar Constant: No

Munchausen Constant: No

Armstrong Number: No

Kaprekar Number: No

Catalan Number: No

Vampire Number: No

Taxicab Number: No

Super Prime: No

Friedman Number: No

Fermat Number: No

Cullen Number: No

OEIS Sequences

Canonical enumeration of integers: interleaved positive and negative integers with zero prepended. A1057

a(n) = n * μ(n), where μ is the Möbius function A008683. A55615

a(0) = 0; thereafter a(n) is the least integer (in absolute value) not yet in the sequence such that the absolute difference between a(n-1) and a(n) is a square; in case of a tie, preference is given to the positive value. A377091

Generalized sum of divisors function: excess of sum of odd divisors of n over sum of even divisors of n. A2129

a(n) = 2 - n. A22958

Balanced ternary enumeration (based on balanced ternary representation) of integers; write n in ternary and then replace 2's with (-1)'s. A117966

Triangle read by rows: The n-th derivative of the logistic function written in terms of y, where y = 1/(1 + exp(-x)). A163626

a(0)=0; thereafter a(2n) = 2a(n), a(2n+1) = -2a(n) + 1. A65620

A permutation of the integers: a(n) = (-1)ⁿ * floor( (n+1)/2 ). A130472

a(n) = A070080(n)² + A070081(n)² - A070082(n)². A70085