Properties of the Number 20506

Twenty Thousand Five Hundred Six

Basics

Value: 20505 → 20506 → 20507

Parity: even

Prime: No

Previous Prime: 20483

Next Prime: 20507

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 2 × 10253

Divisors: 1, 2, 10253, 20506

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000000011010

Octal: 50032

Duodecimal: BA4A

Hexadecimal: 501a

Square: 420496036

Square Root: 143.19916200872126

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 T(n,k) of entries in the k-th last blocks of all set partitions of [n]; triangle T(n,k), n>=1, 1<=k<=n, read by rows. A286416

a(n) = ∑_k=0..n q(n,k) * !k, where q(n,k) = number of partitions of n into k distinct parts and !k = subfactorial of k. A331518

Expansion of q^-3/4 * η(q²)² * η(q²⁰) / (η(q)² * η(q⁴)) in powers of q. A146163

Numbers k such that the continued fraction for sqrt(k) has period 91. A20430

Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 11. A31599

Expansion of η(q⁶)³ * η(q¹⁰)³ / (η(q²) * η(q³)² * η(q⁵)² * η(q³⁰)) in powers of q. A257632

Numbers which contain exactly the same digits (with the correct multiplicity) in 3 different smaller bases. A59828

Numbers with record number of iterations of x -> A306938(x) required to reach 1 (A306944). A306978

Cyclotomic polynomials at x = -7. A20506