Properties of the Number 21045

Twenty-One Thousand Forty-Five

Basics

Value: 21044 → 21045 → 21046

Parity: odd

Prime: No

Previous Prime: 21031

Next Prime: 21059

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 3 × 5 × 23 × 61

Divisors: 1, 3, 5, 15, 23, 61, 69, 115, 183, 305

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001000110101

Octal: 51065

Duodecimal: 10219

Hexadecimal: 5235

Square: 442892025

Square Root: 145.06894912420094

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

Heinz numbers of integer partitions whose reciprocal sum is 1. A316855

Heinz numbers of aperiodic integer partitions into relatively prime parts whose reciprocal sum is 1. A316888

Composite squarefree numbers k such that the arithmetic mean of the distinct prime factors of k is a prime p, and p divides k. A229094

Number of n element multisets of the 15th roots of unity with zero sum. A321418

E.g.f.: exp( ∑_n>=1 n!*x^2·n/(2·n)! ) = ∑_n>=0 a(n)*x^2·n/(2·n)!. A193444

Analog of A265434 that counts only primitive words. A276408

Heinz numbers of integer partitions into relatively prime parts whose reciprocal sum is 1. A316890

Numbers n such that σ(n+1)-σ(n) = -σ(n)/d(n), where d(n) denotes the number of divisors of n. A66177

a(n) = 3·a(n-1) + a(n-2) + n. A117917

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 569", based on the 5-celled von Neumann neighborhood. A272993