Properties of the Number 21670

Twenty-One Thousand Six Hundred Seventy

Basics

Value: 21669 → 21670 → 21671

Parity: even

Prime: No

Previous Prime: 21661

Next Prime: 21673

Digit Sum: 16

Digital Root: 7

Palindrome: No

Factorization: 2 × 5 × 11 × 197

Divisors: 1, 2, 5, 10, 11, 22, 55, 110, 197, 394

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010010100110

Octal: 52246

Duodecimal: 1065A

Hexadecimal: 54a6

Square: 469588900

Square Root: 147.20733677368122

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 permutations of {1..n} with n inversions. A128566

Triangle, read by rows, where T(n,k) equals the number of permutations of {1..n+1} with [(nk+k)/2] inversions for n>=k>=0. A128564

Expansion of (1-x-2x²+sqrt(1-2x-3x²))/(2(1-x)(1-2x-3x²)). A116409

Coordination sequence for σ-CrFe, Position Xf. A9958

Binomial (Binomial (n,2), 3) - Binomial (Binomial (n,3), 2). A93567

Derived from the centered polygonal numbers: start with the first triangular number, then the sum of the first square number and the second triangular number, then the sum of first pentagonal number, the second square number and the third triangular number, and so on and so on... A141534

Number of reduced words of length n in the Weyl group A₉. A161457

First occurrence of n consecutive n's in the decimal expansion of the Copeland-Erdos constant. A224897

Triangle of Mahonian numbers T(n,k): coefficients in expansion of ∏_i=0..n-1 (1 + x + ... + xⁱ), where k ranges from 0 to A000217(n-1). Also enumerates permutations by their major index. A8302

Decimal expansion of 1/666. A21670