Properties of the Number 20181

Twenty Thousand One Hundred Eighty-One

Basics

Value: 20180 → 20181 → 20182

Parity: odd

Prime: No

Previous Prime: 20177

Next Prime: 20183

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 3 × 7 × 31 ²

Divisors: 1, 3, 7, 21, 31, 93, 217, 651, 961, 2883

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 100111011010101

Octal: 47325

Duodecimal: B819

Hexadecimal: 4ed5

Square: 407272761

Square Root: 142.05984654363104

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

Triangle read by rows: 2-Stirling numbers of the second kind. A143494

L-matrix for Euler numbers A000111(n+1). A147315

Expansion of ∑_k>0 x^3·k/(1-x^k)⁴. A363607

a(n) = 21·n². A64762

Triangle read by rows: matrix product of the Stirling numbers of the second kind with the binomial coefficients. A126351

Triangle read by rows. The incomplete Bell transform of the swinging factorials A056040. A352363

a(n) = sigma₁(n) * sigma₂(n). A379812

Number of base 13 n-digit numbers with adjacent digits differing by three or less. A126481

Triangle read by rows, T(n,k) = ∑_j=0..n (-1)^n-j*C(-j,-n)*S2(j,k), S2 the Stirling set numbers A048993, for n>=0 and 0<=k<=n. A269952

Triangle read by rows: row n gives coefficients of increasing powers of·in the polynomial (-1)ⁿ*p(n), where p(n) is defined as follows. Let f(n) = n*(n+1)/2, g(n) = f(n)+1; then p(-1) = 0, p(0) = 1 and for n >= 1, p(n) = (x - f(n))*p(n - 1) - g(n - 1)²*p(n - 2). A135049