Properties of the Number 21804

Twenty-One Thousand Eight Hundred Four

Basics

Value: 21803 → 21804 → 21805

Parity: even

Prime: No

Previous Prime: 21803

Next Prime: 21817

Digit Sum: 15

Digital Root: 6

Palindrome: No

Factorization: 2 ² × 3 × 23 × 79

Divisors: 1, 2, 3, 4, 6, 12, 23, 46, 69, 79

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010100101100

Octal: 52454

Duodecimal: 10750

Hexadecimal: 552c

Square: 475414416

Square Root: 147.66177569025777

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

T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 2, 3, 4, 5 or 6 king-move adjacent elements, with upper left element zero. A299060

Iterations at which Langton's Ant living on triangular tiling reaches the distance of n from the origin for the first time. A275303

E.g.f. satisfies A(x) = 1 + A(x)³ * log(1 + x). A367155

Expansion of e.g.f. 1/(1 - x + log(1 - 3·x)/3). A367852

Numbers k such that k + sum of its prime factors = (k+1) + sum of its prime factors. A20700

a(n) = n*(14·n + 13) + 3. A195029

Expansion of ∏_k>=0 1/(1 + x^3·k+1)^3·k+1. A285286

Numbers k such that s(k) = s(k+1), where s(k) is A059975. A327250

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 203", based on the 5-celled von Neumann neighborhood. A270727

Number of nX3 0..1 arrays with every element equal to 0, 2, 3, 4, 5 or 6 king-move adjacent elements, with upper left element zero. A299055