Properties of the Number 21186

Twenty-One Thousand One Hundred Eighty-Six

Basics

Value: 21185 → 21186 → 21187

Parity: even

Prime: No

Previous Prime: 21179

Next Prime: 21187

Digit Sum: 18

Digital Root: 9

Palindrome: No

Factorization: 2 × 3 ² × 11 × 107

Divisors: 1, 2, 3, 6, 9, 11, 18, 22, 33, 66

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001011000010

Octal: 51302

Duodecimal: 10316

Hexadecimal: 52c2

Square: 448846596

Square Root: 145.55411364849843

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 n X k 0..1 arrays with no 1 equal to more than one of its horizontal, diagonal and antidiagonal neighbors, with the exception of exactly one element. A283572

Sum over all partitions of n of the LCM of the parts. A181844

T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row and column sum equal to 2 3 4 6 or 7 and every 3X3 diagonal and antidiagonal sum not equal to 2 3 4 6 or 7. A252167

Sum of the squares of the first n Fibonacci numbers with index divisible by 4. A156086

Number of 1 up, 3 down, 5 up, 7 down, ... permutations of [n]. A227941

Numbers that occur in range of A324580. A324541

Structured snub dodecahedral numbers. A100151

11 times pentagonal numbers: 11·n*(3n-1)/2. A153449

a(n) counts the distinct cubical (on alphabet of 3 symbols) billiard words with length n, acting as prefix to just k = 1 such word of length n+1 (that is, not "special"). A180437

Lower Beatty array of sqrt(2). A182639