Properties of the Number 81440

Eighty-One Thousand Four Hundred Forty

Basics

Value: 81439 → 81440 → 81441

Parity: even

Prime: No

Previous Prime: 81439

Next Prime: 81457

Digit Sum: 17

Digital Root: 8

Palindrome: No

Factorization: 2 ⁵ × 5 × 509

Divisors: 1, 2, 4, 5, 8, 10, 16, 20, 32, 40

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2730 Try Today's Challenge

Representations

Binary: 10011111000100000

Octal: 237040

Duodecimal: 3B168

Hexadecimal: 13e20

Square: 6632473600

Square Root: 285.3769437077915

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

T(n,k)=Number of 2nX2k 0..4 arrays with values 0..4 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors. A198253

Period (multiplicative order base 10) of the terms in A116074 and A116075. A116076

a(n) = ∑_{k=0..floor(n/3)} 2^n-3·k * binomial(2·k+1,2·n-6·k+1). A387652

Number of 2nX6 0..4 arrays with values 0..4 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors. A198248

Number of 2nX8 0..4 arrays with values 0..4 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors. A198249

Numbers whose base-5 representation has exactly 8 runs. A43608

Number of walks within N³ (the first octant of Z³) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 0), (-1, 0, 1), (0, -1, 0), (1, 1, 0), (1, 1, 1)}. A151023

Order of alternating group A_n, or number of even permutations of n letters. A1710

Expansion of e.g.f.: exp(x)*cosh(x/sqrt(1 - x²)). A81440