Properties of the Number 21105

Twenty-One Thousand One Hundred Five

Basics

Value: 21104 → 21105 → 21106

Parity: odd

Prime: No

Previous Prime: 21101

Next Prime: 21107

Digit Sum: 9

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 5 × 7 × 67

Divisors: 1, 3, 5, 7, 9, 15, 21, 35, 45, 63

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001001110001

Octal: 51161

Duodecimal: 10269

Hexadecimal: 5271

Square: 445421025

Square Root: 145.275600153639

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

Odd primitive abundant numbers. A6038

a(n) is the concatenation of n and 5n. A19553

Irregular triangle of odd primitive abundant numbers (A006038) in which row n has numbers with n distinct prime factors. A188439

Number of directed multigraphs with loops on 3 nodes with n arcs. A50927

Odd recursive abundant numbers: odd numbers k such that A333926(k) > 2·k. A333950

Primitive terms of A388034. A388035

Numbers that, when expressed in base 3 and then interpreted in base 10, yield a multiple of the original number. A32537

Number of periodic palindromic structures of length n using exactly four different symbols. A56510

Triangle T, read by rows, equal to the matrix inverse of the triangle defined by [T^-1](n,k) = (n-k)!*A008278(n+1,k+1), for n>=k>=0, where A008278 is a triangle of Stirling numbers of 2nd kind. A106340

Odd primitive abundant numbers n such that n = x² + x + y² with y² < 2·x; a subsequence of A006038. A136476