Properties of the Number 21800

Twenty-One Thousand Eight Hundred

Basics

Value: 21799 → 21800 → 21801

Parity: even

Prime: No

Previous Prime: 21799

Next Prime: 21803

Digit Sum: 11

Digital Root: 2

Palindrome: No

Factorization: 2 ³ × 5 ² × 109

Divisors: 1, 2, 4, 5, 8, 10, 20, 25, 40, 50

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010100101000

Octal: 52450

Duodecimal: 10748

Hexadecimal: 5528

Square: 475240000

Square Root: 147.648230602334

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

Array read by antidiagonals: T(n,k) = number of rooted n-dimensional polycubes with k cells, with no symmetries removed (n >= 1, k >= 1). A48790

Array read by antidiagonals: T(n,k) = number of rooted 2-dimensional polyominoes with k cells, the cells being regular n-gons, with no symmetries removed. A94166

Irregular table whose rows list the nontrivial cycles of the ghost iteration A329201, starting with the smallest member. A329342

Number of rooted 2-dimensional polyominoes with n square cells, with no symmetries removed. A48664

Numbers n such that φ(n) is the sum of the first k divisors of n for some k. A72278

Percolation series for directed square lattice. A6462

a(n) = ∑_k=1..n k*(prime(k) - k). A110477

Total sum of parts which are powers of 2 in all partitions of n. A342231

Number of partitions satisfying cn(0,5) + cn(1,5) + cn(4,5) <= cn(2,5) + cn(3,5). A39878

Length of the n-th nontrivial cycle of the "ghost iteration" A329200. A329197