Properties of the Number 21318

Twenty-One Thousand Three Hundred Eighteen

Basics

Value: 21317 → 21318 → 21319

Parity: even

Prime: No

Previous Prime: 21317

Next Prime: 21319

Digit Sum: 15

Digital Root: 6

Palindrome: No

Factorization: 2 × 3 × 11 × 17 × 19

Divisors: 1, 2, 3, 6, 11, 17, 19, 22, 33, 34

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001101000110

Octal: 51506

Duodecimal: 10406

Hexadecimal: 5346

Square: 454457124

Square Root: 146.00684915441468

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

a(n) = binomial(3·n+1,n)/(n+1). A6013

If n = 2·m then a(n) = binomial(3·m, m)/(2·m+1), if n=2·m+1 then a(n) = binomial(3·m+1, m+1)/(2·m+1). A47749

Number of dissectable polyhedra with n tetrahedral cells and symmetry of type I. A47753

Numbers k such that σ(k) = 9*φ(k). A163667

Triangle read by rows: T(n,k) is the number of noncrossing trees with root degree equal to k. A92276

Number of dissectable polyhedra with n tetrahedral cells and symmetry of type P. A47765

Number of dissectable polyhedra with n tetrahedral cells and symmetry of type D. A47773

Split positive integers into extending even groups and sum: 1+2, 3+4+5+6, 7+8+9+10+11+12, 13+14+15+16+17+18+19+20, ... A61317

Expansion of (1-4·x)^11/2. A20923

Row sums of the triangular array A246694. A246695