Properties of the Number 21645

Twenty-One Thousand Six Hundred Forty-Five

Basics

Value: 21644 → 21645 → 21646

Parity: odd

Prime: No

Previous Prime: 21617

Next Prime: 21647

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 5 × 13 × 37

Divisors: 1, 3, 5, 9, 13, 15, 37, 39, 45, 65

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010010001101

Octal: 52215

Duodecimal: 10639

Hexadecimal: 548d

Square: 468506025

Square Root: 147.12239802287073

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

Number of ways of writing n as the sum of 10 triangular numbers from A000217. A226254

Total number of prime parts in all partitions of n. A37032

Number of multigraphs with 4 nodes and n edges. A3082

Structured disdyakis dodecahedral numbers (vertex structure 7). A100162

Numbers n such that φ(n) + 6 | σ(n). A15797

Number of walks within N² (the first quadrant of Z²) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(-1, -1), (-1, 0), (-1, 1), (0, -1), (1, 0), (1, 1)}. A151467

a(n) is the smallest number such that a(n)*n is an anagram of a(n)*5. A175694

Numbers k such that (52·10^k + 119)/9 is prime. A294229

Nonprime numbers k of the form 4·m+1 such that ∑_j=0..k-1 2^j * binomial(3·j, j) == 1 (mod k). A373747

Inverse of 33rd cyclotomic polynomial. A14042