Properties of the Number 21121

Twenty-One Thousand One Hundred Twenty-One

Basics

Value: 21120 → 21121 → 21122

Parity: odd

Prime: Yes

Previous Prime: 21107

Next Prime: 21139

Digit Sum: 7

Digital Root: 7

Palindrome: No

Factorization: 21121

Divisors: 1, 21121

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001010000001

Octal: 51201

Duodecimal: 10281

Hexadecimal: 5281

Square: 446096641

Square Root: 145.33065746772084

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

Primes having only {1, 2, 9} as digits. A385776

Primes having only {0, 1, 2} as digits. A36953

Primes that contain digits 1 and 2 only. A20450

Primes having only {1, 2, 4} as digits. A260267

Define a pair of sequences by p(0) = 0, q(0) = p(1) = q(1) = 1, q(n+1) = p(n)*q(n-1), p(n+1) = q(n+1) + q(n) for n > 0; then a(n) = p(n) and A064183(n) = q(n). A64526

Stirling transform of (n!)². A64618

Primes with digital product = 4. A107690

Centered 40-gonal numbers. A195317

Least prime in A031936 (lesser of 18-twins) whose distance to the next 18-twin is 2·n. A52358

List of primitive words over the alphabet {1,2}. A213969