Properties of the Number 20981

Twenty Thousand Nine Hundred Eighty-One

Basics

Value: 20980 → 20981 → 20982

Parity: odd

Prime: Yes

Previous Prime: 20963

Next Prime: 20983

Digit Sum: 20

Digital Root: 2

Palindrome: No

Factorization: 20981

Divisors: 1, 20981

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101000111110101

Octal: 50765

Duodecimal: 10185

Hexadecimal: 51f5

Square: 440202361

Square Root: 144.8481963988506

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

Least n-gap prime: a(n) = least prime p for which there is no prime between n·p and n·q, where q is the next prime after p. A195325

Primes p with p + 2 and prime(p) - 2 both prime. A236467

Primes whose digits can be arranged in increasing cyclic order - to form a substring of 123456789012345678901234567890... A68710

List of strictly non-palindromic twin primes {p, p+2}. A138329

Positive numbers y such that y² is of the form x²+(x+191)² with integer x. A161487

Primes 8k + 5 at the end of the maximal gaps in A269513. A269515

a(n) = (A085249(n) - 1)/6. A88349

Lesser of a twin-prime pair where both are expressible as the sum of two triangular numbers. A118638

Lesser of twin primes such that both twin primes have no bases b, 1 < b < p-1, in which p is a palindrome. A138348

Records of A195325. A195329