Properties of the Number 20891

Twenty Thousand Eight Hundred Ninety-One

Basics

Value: 20890 → 20891 → 20892

Parity: odd

Prime: No

Previous Prime: 20887

Next Prime: 20897

Digit Sum: 20

Digital Root: 2

Palindrome: No

Factorization: 13 × 1607

Divisors: 1, 13, 1607, 20891

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101000110011011

Octal: 50633

Duodecimal: 1010B

Hexadecimal: 519b

Square: 436433881

Square Root: 144.53719244540486

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 of matroids of rank 2 on n labeled points. A58681

T(n,k) = number of nonnegative integer arrays of length n+k-1 with new values 0 upwards introduced in order, and containing the value k-1. A211561

Triangle T(n,k) of number of strongly connected digraphs on n unlabeled nodes and with k arcs, k=0..n*(n-1). A57276

Expansion of ψ(x²) / f(-x) in powers of·where ψ(), f() are Ramanujan θ functions. A98613

G.f.: ∏_k>=1 1/(1-x^k)^3·k+2. A255803

Triangle read by rows, A008277·A000012. A137650

Triangle T(n,k) read by rows, giving number of matroids of rank k on n labeled points (n >= 0, 0 <= k <= n). A58669

Determinant of n X n Hankel matrix whose entries are t(i+j), 0 <= i, j < n, where t is the Thue-Morse sequence. A56887

Fourth column of A046741. A62124

A triangular array of numbers related to factorization and number of parts in Murasaki diagrams. A133611