Properties of the Number 21440

Twenty-One Thousand Four Hundred Forty

Basics

Value: 21439 → 21440 → 21441

Parity: even

Prime: No

Previous Prime: 21433

Next Prime: 21467

Digit Sum: 11

Digital Root: 2

Palindrome: No

Factorization: 2 ⁶ × 5 × 67

Divisors: 1, 2, 4, 5, 8, 10, 16, 20, 32, 40

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2730 Try Today's Challenge

Representations

Binary: 101001111000000

Octal: 51700

Duodecimal: 104A8

Hexadecimal: 53c0

Square: 459673600

Square Root: 146.424041741785

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

Coordination sequence for 4-dimensional cubic lattice (points on surface of 4-dimensional cross-polytope). A8412

Number of 10-almost primes k such that 2ⁿ < k <= 2ⁿ⁺¹. A120041

Number of n-step self-avoiding walks on hexagonal lattice from (0,0) to (0,2). A3290

Coordination sequence for C₄ lattice. A19560

Expansion of (1/x) * Series_Reversion( x*(1-x)⁴/(1+x)⁴ ). A365847

Triangle read by rows: T(n,k) is the number of unsensed combinatorial maps with n edges and k vertices, 1 <= k <= n + 1. A380616

Square array T(n,k), n >= 0, k >= 0, read by antidiagonals, where T(n,k) is the coefficient of x^k·n in expansion of ( (1 + x)/(1 - x) )ⁿ. A336521

Number of unsensed combinatorial maps with n edges and 3 vertices. A380621

Number of series-parallel networks with n edges. A1677

a(n) = 2·a(n-1) - 2*(n-2)*a(n-2), with a(0)=1, a(1)=2. A122033