Properties of the Number 21518

Twenty-One Thousand Five Hundred Eighteen

Basics

Value: 21517 → 21518 → 21519

Parity: even

Prime: No

Previous Prime: 21517

Next Prime: 21521

Digit Sum: 17

Digital Root: 8

Palindrome: No

Factorization: 2 × 7 × 29 × 53

Divisors: 1, 2, 7, 14, 29, 53, 58, 106, 203, 371

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010000001110

Octal: 52016

Duodecimal: 10552

Hexadecimal: 540e

Square: 463024324

Square Root: 146.69014963520897

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 graphical partitions (degree-vectors for graphs with n vertices, allowing self-loops which count as degree 1; or possible ordered row-sum vectors for a symmetric 0-1 matrix). A29889

T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row and column sum 2 4 5 or 7 and every diagonal and antidiagonal sum not 2 4 5 or 7. A251923

Numbers k whose binary expansion contains 2 adjacent 1's and A391571(k) = k. A391581

Number of ways to reach n by starting with 1 and repeatedly adding any positive integer or multiplying by any integer greater than 1. A348396

Number of (n+2)X(1+2) 0..3 arrays with every 3X3 subblock row and column sum 2 4 5 or 7 and every diagonal and antidiagonal sum not 2 4 5 or 7. A251916

Number of compositions of n such that the maximal distance between two identical parts equals four. A262197

Zero-avoiding Fibonacci sequence: a(n) is the largest zeroless number that can be written as a(i) + a(j) where 1 <= i < j < n with a(1) = a(2) = 1. A374924

Sequence relating to the benzene ring. A120262

a(n) = n*(2·n - 3 - (-1)ⁿ)*(11·n + (-1)ⁿ)/24. A308026

Decimal expansion of 1/514. A21518