Properties of the Number 21897

Twenty-One Thousand Eight Hundred Ninety-Seven

Basics

Value: 21896 → 21897 → 21898

Parity: odd

Prime: No

Previous Prime: 21893

Next Prime: 21911

Digit Sum: 27

Digital Root: 9

Palindrome: No

Factorization: 3 ³ × 811

Divisors: 1, 3, 9, 27, 811, 2433, 7299, 21897

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010110001001

Octal: 52611

Duodecimal: 10809

Hexadecimal: 5589

Square: 479478609

Square Root: 147.9763494616623

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 nonnegative integer arrays of length n+2k+1 with new values 0 upwards introduced in order, no three adjacent elements all unequal, and containing the value k+1. A211849

a(1)=3; for n > 1, a(n) = 1 + a(n-1) + gcd( a(n-1)*(a(n-1)+2), A073829(a(n-1)) ). A167053

a(n) = (n - 1)*(n² + n - 1). A33445

Place n points on each of the three sides of a triangle, 3n points in all; a(n) = number of nondegenerate triangles that can be constructed using these points (plus the 3 original vertices) as vertices. A130748

Number of ways to write prime(n) as sum of distinct divisors of prime(n)+1. A85496

E.g.f.: ∑_n>=0 (exp(3ⁿ*x) - 1)ⁿ/n!, an analog of the Bell numbers (A000110). A168408

Irregular triangle read by rows: T(n,k) = number of unsigned unichromosonal genomes with n genes at 3-break distance k from a fixed genome, 0 <= k <= floor(n/2). A264614

a(n) = n·a(n-1) + (1/2)*(1+(-1)ⁿ), a(0)=0. A80227

Numerator of Euler(n, 1/28). A157206

Number of (n+1) X (2+1) 0..1 arrays with each row divisible by 3 and each column divisible by 5, read as a binary number with top and left being the most significant bits. A262466