Properties of the Number 20811

Twenty Thousand Eight Hundred Eleven

Basics

Value: 20810 → 20811 → 20812

Parity: odd

Prime: No

Previous Prime: 20809

Next Prime: 20849

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 3 × 7 × 991

Divisors: 1, 3, 7, 21, 991, 2973, 6937, 20811

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000101001011

Octal: 50513

Duodecimal: 10063

Hexadecimal: 514b

Square: 433097721

Square Root: 144.2601816164114

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 k and k + 1 are both Niven numbers in base 3/2 (A342426). A342427

a(n) = a(n-1) + a(n-9) for n >= 9; a(n) = 1 for n=0..7; a(8) = 2. A5711

a(n) = number of steps to reach 0 when starting from k = (n³)-1 and repeatedly applying the map that replaces k with k - A055401(k), where A055401(k) = the number of positive cubes needed to sum to k using the greedy algorithm. A261228

T(n,k)=Number of nXk 0..1 arrays with each 1 adjacent to 1, 3 or 5 king-move neighboring 1s. A296952

Riordan array ( (1/(1-x))^m , x·A000108(x) ), m =4. A185945

Indices of primes in sequence defined by A(0) = 61, A(n) = 10·A(n-1) - 9 for n > 0. A101517

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 913", based on the 5-celled von Neumann neighborhood. A273768

Number of n X 3 0..1 arrays with each 1 adjacent to 1, 3 or 5 king-move neighboring 1s. A296947

Expansion of 1/(1 - x * (1 + x⁴)²). A373706

Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 96. A31594