Properties of the Number 21909

Twenty-One Thousand Nine Hundred Nine

Basics

Value: 21908 → 21909 → 21910

Parity: odd

Prime: No

Previous Prime: 21893

Next Prime: 21911

Digit Sum: 21

Digital Root: 3

Palindrome: No

Factorization: 3 × 67 × 109

Divisors: 1, 3, 67, 109, 201, 327, 7303, 21909

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010110010101

Octal: 52625

Duodecimal: 10819

Hexadecimal: 5595

Square: 480004281

Square Root: 148.0168909280289

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(1)=3; for n > 1, a(n) = 1 + a(n-1) + gcd( a(n-1)*(a(n-1)+2), A073829(a(n-1)) ). A167053

a(n) = a(n-1)² + n, with a(0)=0. A98152

a(n) is the minimum sum of a nonnegative integer 4-tuple that takes n moves to reach a 0 component, where a move picks two components, subtracts the smaller from the larger, and doubles the smaller. A383586

Total number of ON cells in the "Ulam-Warburton" two-dimensional cellular automaton of A147562 after A048645(n) generations. A255264

Number of meanders of length n with Motzkin-steps avoiding the consecutive steps UD and HH. A329675

Floor of area of triangle whose sides are consecutive Ulam numbers (A002858). A330909

Number of partitions of n into parts not of the form 21k, 21k+8 or 21k-8. Also number of partitions with at most 7 parts of size 1 and differences between parts at distance 9 are greater than 1. A35986

Partial sums of A299037. A299767

Decimal expansion of 1/905. A21909