Properties of the Number 21782

Twenty-One Thousand Seven Hundred Eighty-Two

Basics

Value: 21781 → 21782 → 21783

Parity: even

Prime: No

Previous Prime: 21773

Next Prime: 21787

Digit Sum: 20

Digital Root: 2

Palindrome: No

Factorization: 2 × 10891

Divisors: 1, 2, 10891, 21782

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101010100010110

Octal: 52426

Duodecimal: 10732

Hexadecimal: 5516

Square: 474455524

Square Root: 147.5872623230067

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

Triangle read by rows: T(n,k) is the number of simple connected graphs on n vertices having independence number k. A294490

Expansion of (1 + x² - x³)/((1 + x² - x³)² - 4·x²). A376726

Number of simple connected graphs on n nodes whose independence number a(g)=5. A243784

a(0) = 1, a(n) = 20·n² + 2 for n>0. A10010

Expansion of 1 / ((1-x)⁴ - x⁶). A392542

Numbers n such that σ(σ(φ(n))) = σ(σ(n)). A172466

Arises in a coin-weighing problem. A293948

Number of 123-avoiding stabilized-interval-free permutations of size n. A363431

Square array read by antidiagonals, where the n-th row is the coordination sequence of a certain tiling with an n-dimensional analog of the X pentomino (or Greek cross), n >= 1. A383338

T(n,k)=Number of (n+3)X(k+3) 0..1 matrices with each 4X4 subblock idempotent. A224568