Properties of the Number 20905

Twenty Thousand Nine Hundred Five

Basics

Value: 20904 → 20905 → 20906

Parity: odd

Prime: No

Previous Prime: 20903

Next Prime: 20921

Digit Sum: 16

Digital Root: 7

Palindrome: No

Factorization: 5 × 37 × 113

Divisors: 1, 5, 37, 113, 185, 565, 4181, 20905

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000110101001

Octal: 50651

Duodecimal: 10121

Hexadecimal: 51a9

Square: 437019025

Square Root: 144.5856147754679

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

Fibonacci sequence beginning 0, 5. A22088

Sum of two consecutive squares of Lucas numbers (A001254). A106729

Numbers that are the sum of seven fifth powers in two or more ways. A345605

Numbers that are the sum of seven fifth powers in exactly two ways. A346279

G.f. A(x) satisfies A(x) = 1 + x·A(x)² / (1 - x·A(x)⁴). A364739

Numerators of A178381(4·n+1)/A178381(4·n). A179131

Square array read by upward antidiagonals: T(n, k) is the number of n-ary strings of length k containing 00. A340156

Numbers of the form p·q*r where p, q, r are distinct primes congruent to 1 mod 4 such that Legendre(p/q) = Legendre(p/r) = Legendre(q/r) = -1. A323271

G.f. A(x) satisfies: A(x) = 1 / ((1 + x) * (1 - x·A(2·x))). A348860

The number of quaternary strings of length n containing 00. A351529