Properties of the Number 20565

Twenty Thousand Five Hundred Sixty-Five

Basics

Value: 20564 → 20565 → 20566

Parity: odd

Prime: No

Previous Prime: 20563

Next Prime: 20593

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 5 × 457

Divisors: 1, 3, 5, 9, 15, 45, 457, 1371, 2285, 4113

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000001010101

Octal: 50125

Duodecimal: BA99

Hexadecimal: 5055

Square: 422919225

Square Root: 143.40502083260543

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(n,k) is the n-th Rhonda number to base A002808(k), the k-th composite number; square array A(n,k), n>=1, k>=1, read by antidiagonals. A291925

Number of strict integer partitions with sum <= n that can be linearly combined using nonnegative coefficients to obtain n. A365311

Integers that are Rhonda numbers to base 14. A100972

Numbers k such that k² - 1 is a palindrome. A70253

E.g.f.: ∑_n>=0 ((1+x)ⁿ + 4)ⁿ * xⁿ/n!. A326094

Numbers n such that Catalan(n)-1 is prime. A53427

Expansion of b(3)*b(4)/(1 - 2·x + x⁵), where b(k) = (1-x^k)/(1-x). A266337

A106486-encodings of combinatorial games with value 2. A125995

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 169", based on the 5-celled von Neumann neighborhood. A270463

Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 0100-0100-1111 pattern in any orientation. A146574