Properties of the Number 20961

Twenty Thousand Nine Hundred Sixty-One

Basics

Value: 20960 → 20961 → 20962

Parity: odd

Prime: No

Previous Prime: 20959

Next Prime: 20963

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 17 × 137

Divisors: 1, 3, 9, 17, 51, 137, 153, 411, 1233, 2329

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101000111100001

Octal: 50741

Duodecimal: 10169

Hexadecimal: 51e1

Square: 439363521

Square Root: 144.77914214416384

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) = (n⁴ + n² + 2·n)/4. A6528

Divisors of 10¹⁶ - 1. A111211

a(n) = n! * ∑_k=0..n (-1)^n-k * binomial(k+4,5) / k!. A368587

Irregular triangle read by rows: T(n,k) is the number of polyominoes of size k, i.e., connected subsets of k square cells (or vertices), of the n X n flat torus, up to cyclic shifts and reflections of rows and columns; 1 <= k <= n². A385383

Numbers a = b + c where a, b, and c contain the same decimal digits. A203024

Pseudoprimes to base 10 that are not squarefree. A306449

Expansion of e.g.f. exp(x/(1 - 2·x)²). A380639

a(n) = ∑_{k >= 1} floor(n*φ^3-k). A20961

Number of (n+1)X(2+1) 0..3 arrays with every element next to itself plus and minus one within the range 0..3 horizontally, vertically or antidiagonally, with no adjacent elements equal. A232385