Properties of the Number 19905

Nineteen Thousand Nine Hundred Five

Basics

Value: 19904 → 19905 → 19906

Parity: odd

Prime: No

Previous Prime: 19891

Next Prime: 19913

Digit Sum: 24

Digital Root: 6

Palindrome: No

Factorization: 3 × 5 × 1327

Divisors: 1, 3, 5, 15, 1327, 3981, 6635, 19905

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 100110111000001

Octal: 46701

Duodecimal: B629

Hexadecimal: 4dc1

Square: 396209025

Square Root: 141.08508071373103

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 pairs of partitions of [n] whose join is the partition {{1,2,...,n}}. A60639

Number of polyominoes with n cells that tile the plane by translation or by 180-degree rotation (Conway criterion). A75203

Regular triangle where T(n,k) is the number of pairs of set partitions of {1,...,n} with join of length k. A318392

Expansion of g.f. (1 + x + 2·x²)/((1 - x)³*(1 - x³)). A92498

Triangle T(n, k) = Numbers of inequivalent (mod D₃) ways to place k points on a triangular grid of side n so that no three of them are vertices of an equilateral triangle of any orientation. Triangle read by rows. A243141

a(n) = dot_product(n,n-1,...2,1)*(5,6,...,n,1,2,3,4). A26060

Molien series for invariants of finite Coxeter group A₉. A266778

Principal diagonal of the convolution array A213822. A213823

Number of nonisomorphic semigroups with n elements satisfying the equation xyz = xz. A390162

Number of invertible circulant (0,1) matrices over the reals that have even determinant. A86479