Properties of the Number 21981

Twenty-One Thousand Nine Hundred Eighty-One

Basics

Value: 21980 → 21981 → 21982

Parity: odd

Prime: No

Previous Prime: 21977

Next Prime: 21991

Digit Sum: 21

Digital Root: 3

Palindrome: No

Factorization: 3 × 17 × 431

Divisors: 1, 3, 17, 51, 431, 1293, 7327, 21981

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010111011101

Octal: 52735

Duodecimal: 10879

Hexadecimal: 55dd

Square: 483164361

Square Root: 148.25990692024598

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

Smallest k>n such that n³+1 divides k·n²+1. A71568

The number of hanging vertically stable self-avoiding walks of length n on a 3D cubic lattice where both the nodes and connecting rods have mass. A337761

Expansion of ∏_k>=1 (1+x^k)^A000129(k). A261331

Least k such that the first k terms of A006928 contain n more 2's than 1's. A25507

A Jacobsthal convolution. A113726

Indices in A006928 where the imbalance between 1's and 2's sets a new record. A274775

Column 7 of triangle A055898. A55903

Number of 2 X n arrays of the minimum value of corresponding elements and their horizontal, vertical or diagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..3 2 X n array. A220205

Number of ways to write n as an ordered sum of 6 prime power palindromes (A084092). A282845

G.f. satisfies A(x) = 1 + x·A(x)²*(1 + x³*A(x)). A365267