Properties of the Number 20815

Twenty Thousand Eight Hundred Fifteen

Basics

Value: 20814 → 20815 → 20816

Parity: odd

Prime: No

Previous Prime: 20809

Next Prime: 20849

Digit Sum: 16

Digital Root: 7

Palindrome: No

Factorization: 5 × 23 × 181

Divisors: 1, 5, 23, 115, 181, 905, 4163, 20815

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000101001111

Octal: 50517

Duodecimal: 10067

Hexadecimal: 514f

Square: 433264225

Square Root: 144.27404478976806

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

T(n,k)=Number of (n+2)X(k+2) 0..1 arrays with every 3X3 subblock sum of the two sums of the diagonal and antidiagonal minus the two minimums of the central column and central row nondecreasing horizontally and vertically. A257209

Triangle T(n, k) = T(n-1, k) + T(n, k-1) + T(n-1, k-1) + T(n-2, k-1), with T(n, 1) = T(n, n) = 1, read by rows. A144447

Integer part of log(n!)^{1 + log(1 + log(1 + n})). A62445

Numbers such that n² = 29 mod 1193. A165989

Number of (n+2)X(2+2) 0..1 arrays with every 3X3 subblock sum of the two sums of the diagonal and antidiagonal minus the two minimums of the central column and central row nondecreasing horizontally and vertically. A257203

Number of (n+2)X(3+2) 0..1 arrays with every 3X3 subblock sum of the two sums of the diagonal and antidiagonal minus the two minimums of the central column and central row nondecreasing horizontally and vertically. A257204

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 929", based on the 5-celled von Neumann neighborhood. A273781

Triangle (read by rows) in which the number of entries in a row only increases by 1 every other row, the first column and the 'diagonal' is set to all 1's and a(i,j) = a(i-1,j) + a(i-1,j-1) + a(i-2,j-1) + a(i-3,j-1) for other entries. A96966

Decimal expansion of 1/sqrt(58). A20815

Pandigital numbers (A171102) of the form 9·prime. A175845