Properties of the Number 21004

Twenty-One Thousand Four

Basics

Value: 21003 → 21004 → 21005

Parity: even

Prime: No

Previous Prime: 21001

Next Prime: 21011

Digit Sum: 7

Digital Root: 7

Palindrome: No

Factorization: 2 ² × 59 × 89

Divisors: 1, 2, 4, 59, 89, 118, 178, 236, 356, 5251

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001000001100

Octal: 51014

Duodecimal: 101A4

Hexadecimal: 520c

Square: 441168016

Square Root: 144.92756811593853

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

Eight bishops and one elephant on a 3 X 3 chessboard. G.f.: (1+x-5·x²)/(1-3·x-x²+6·x³). A175655

Numbers k such that 16·3^k + 1 is prime. A387060

Numbers k such that (σ(k)+σ(k+1))/k is an integer. A68078

Expansion of ∏_k>=1 1/(1 + x^k)^k*(2·k-1). A295121

Numbers n such that σ(n+1)+σ(n)=3n. A67806

5-Smith numbers. A103126

Number of chordless cycles in the n X n queen graph. A361184

Expansion of x*(1-x)/(1-x+2·x³-x⁴). A104554

a(n) is the smallest number k such that d(1)*1! + d(2)*2! + ... + d(p)*p! = n², where d(i) are the decimal digits of k. A198095

Number of nX4 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 0 and 1 1 1 vertically. A207875