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Properties of the Number 21158

Twenty-One Thousand One Hundred Fifty-Eight

Basics

Value: 21157 → 21158 → 21159

Parity: even

Prime: No

Previous Prime: 21157

Next Prime: 21163

Digit Sum: 17

Digital Root: 8

Palindrome: No

Factorization: 2 × 71 × 149

Divisors: 1, 2, 71, 142, 149, 298, 10579, 21158

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001010100110

Octal: 51246

Duodecimal: 102B2

Hexadecimal: 52a6

Square: 447660964

Square Root: 145.45789768864392

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 subsets S of {1,2,...,n} which contain a number that is greater than the sum of the other numbers in S. A95944
T(n,k)=Number of (n+1)X(k+1) 0..1 arrays with the number of rightwards and downwards edge increases in each 2X2 subblock differing from the number in all its horizontal and vertical neighbors. A205072
Irregular triangle read by rows: row n gives numbers of maximal chains of lengths n-1, n, n+1, ... in the Tamari lattice Tn. A282698
a(n) = (n - 2/3)*2n - n/2 + 3/4 - (-1)n/12. A127983
Numbers n such that σ(n) and σ(σ(n)) are both perfect squares. A134263
Number of (n+1) X 2 0..1 arrays with the number of rightwards and downwards edge increases in each 2 X 2 subblock differing from the number in all its horizontal and vertical neighbors. A205065
Number of permutations of [n] avoiding {4231, 1243, 1234}. A294762
Greedy frac multiples of Catalan's constant, G: a(1)=1, ∑n>0 frac(a(n)*x) = 1 at x=G=A006752, where "frac(y)" denotes the fractional part of y. A80158
Number of nX4 0..1 arrays with every element equal to 0, 1, 3, 5, 6 or 8 king-move adjacent elements, with upper left element zero. A299447
Decimal expansion of 1/154. A21158