Properties of the Number 21181

Twenty-One Thousand One Hundred Eighty-One

Basics

Value: 21180 → 21181 → 21182

Parity: odd

Prime: No

Previous Prime: 21179

Next Prime: 21187

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 59 × 359

Divisors: 1, 59, 359, 21181

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001010111101

Octal: 51275

Duodecimal: 10311

Hexadecimal: 52bd

Square: 448634761

Square Root: 145.53693689232298

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

Numbers k such that k·2^m+1 are composites for all exponents m in the range 0<=m<=k. A61153

Composite numbers k such that σ(k + σ(k)) = 2*σ(k). A246858

Row sums of the triangle A322071. A322072

a(n) = Bell(n) + Fibonacci(n). A100388

Numbers k such that 441·2^k+1 is prime. A323149

Multiplicity of highest weight (or singular) vectors associated with character chi₁₅₉ of Monster module. A34547

Least m such that 1 + prime(n)*2^m is a prime, or -1 if no such m exists. A57192

G.f.: A(x) = ∑_n>=0 binomial(3*(n+1), n)/(n+1) * xⁿ / (1+x)^2*(n+1). A316371

Decimal expansion of 1/177. A21181

Table read by rows: each row represents the constant and exponent of a Colbert number. A258074