Properties of the Number 21989

Twenty-One Thousand Nine Hundred Eighty-Nine

Basics

Value: 21988 → 21989 → 21990

Parity: odd

Prime: No

Previous Prime: 21977

Next Prime: 21991

Digit Sum: 29

Digital Root: 2

Palindrome: No

Factorization: 11 × 1999

Divisors: 1, 11, 1999, 21989

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010111100101

Octal: 52745

Duodecimal: 10885

Hexadecimal: 55e5

Square: 483516121

Square Root: 148.2868841131946

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

Numbers k such that the smoothly undulating palindromic number (98·10^k - 89)/99 is a prime. A62232

Number of partitions of n that do not contain 3 as a part. A27337

Expansion of e.g.f. ∏_k>=1 exp(1 - exp(x^k))^1/k!. A346039

Composite numbers whose prime factors contain no digits other than 1 and 9. A36309

Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 74 ones. A31842

a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = (1, p(1), p(2), ...). A24479

Number of walks within N³ (the first octant of Z³) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 1, 1), (0, 1, -1), (1, 0, -1), (1, 1, 1)}. A149691

Numbers k such that A383844(k) and A383844(k+1) are nonzero. A384310

Number of nX4 0..1 arrays with every element equal to 0, 2, 3 or 4 king-move adjacent elements, with upper left element zero. A297911

Decimal expansion of 1/985. A21989