Properties of the Number 20989

Twenty Thousand Nine Hundred Eighty-Nine

Basics

Value: 20988 → 20989 → 20990

Parity: odd

Prime: No

Previous Prime: 20983

Next Prime: 21001

Digit Sum: 28

Digital Root: 1

Palindrome: No

Factorization: 139 × 151

Divisors: 1, 139, 151, 20989

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2730 Try Today's Challenge

Representations

Binary: 101000111111101

Octal: 50775

Duodecimal: 10191

Hexadecimal: 51fd

Square: 440538121

Square Root: 144.8758088847134

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

a(n) = prime(n)*prime(n+2). A90076

Sequence of pairwise relatively prime numbers of class P₄ (see comment in A275246). A275248

Triangle of numbers related to the generalized Catalan sequence C(3;n+1) = A064063(n+1), n>=0. A115154

S₅ sequence in partition of integers > 1 described in A240521. A240522

Semiprimes whose prime factors are of equal binary length and which differ from each other in exactly three bit positions. A261075

Ulam's spiral (SSE spoke). A143839

a(n) is the smallest composite number c such that A002110(n) + c is prime. A38771

Numbers k such that k and k+2 are both A000120-perfect numbers (A175522). A360639

Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 90 ones. A31858

Composite numbers which in base 6 contain their largest proper factor as a substring. A63156