Properties of the Number 21918

Twenty-One Thousand Nine Hundred Eighteen

Basics

Value: 21917 → 21918 → 21919

Parity: even

Prime: No

Previous Prime: 21911

Next Prime: 21929

Digit Sum: 21

Digital Root: 3

Palindrome: No

Factorization: 2 × 3 × 13 × 281

Divisors: 1, 2, 3, 6, 13, 26, 39, 78, 281, 562

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010110011110

Octal: 52636

Duodecimal: 10826

Hexadecimal: 559e

Square: 480398724

Square Root: 148.04728974216312

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

Number of digits in the decimal expansion of the number of partitions of 3ⁿ. A248729

a(n) = round(n*φ¹⁴), where φ is the golden ratio, A001622. A4949

Number of n X 2 0..3 arrays with no element equal to one plus the sum of elements to its left or two plus the sum of elements above it or two plus the sum of the elements diagonally to its northwest, modulo 4. A240359

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 809", based on the 5-celled von Neumann neighborhood. A273612

a(n) = ceiling(n*φ¹⁴), where φ is the golden ratio, A001622. A4969

Array, read by antidiagonals, of the numbers of digits in the decimal expansion of the number of partitions of bⁿ employing a conjectured formula. See both the Comments and the Mathematica coding. A248736

Table read by rows. T(n, k) = ∑_j=0..n-k k·binomial(k, j)*binomial(n - j, k). A364361

Decimal expansion of 1/914. A21918