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Properties of the Number 21628

Twenty-One Thousand Six Hundred Twenty-Eight

Basics

Value: 21627 → 21628 → 21629

Parity: even

Prime: No

Previous Prime: 21617

Next Prime: 21647

Digit Sum: 19

Digital Root: 1

Palindrome: No

Factorization: 2 2 × 5407

Divisors: 1, 2, 4, 5407, 10814, 21628

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010001111100

Octal: 52174

Duodecimal: 10624

Hexadecimal: 547c

Square: 467770384

Square Root: 147.0646116507979

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 equal to a permutation (or rearrangement) of the digits of the sum of their proper divisors. Rearrangements which cause leading zeros are excluded. A85844
Denominators of continued fraction convergents to sqrt(347). A41657
a(n) = smallest number > a(n-1) such that a(1)*a(2)*...*a(n) + 1 and a(1)*a(2)*...*a(n) - 1 are primes. A51956
Array: row n shows the coefficients of the characteristic polynomial of the n-th principal submatrix of (f(i,j)), where f(i,j)=(2i-1 if max(i,j) is odd, and 0 otherwise) as in A204173. A204174
a(n) = a(n-1) + a(n-2) + a([n/3]), where a(0) = 1, a(1) = 2, a(2) = 3. A298341
If n is 0, 1, or prime, a(n) = n; else a(n) = a(n-1) + a(n-2). A265822
Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 630", based on the 5-celled von Neumann neighborhood. A269543
a(n) = binomial(3n,n). A5809
G.f. A(x) satisfies: A(x)3 = x·A( A(x)2 + A(x)3 ). A272485
Numbers k such that 3·5k - 2 is prime. A57917