Properties of the Number 21580

Twenty-One Thousand Five Hundred Eighty

Basics

Value: 21579 → 21580 → 21581

Parity: even

Prime: No

Previous Prime: 21577

Next Prime: 21587

Digit Sum: 16

Digital Root: 7

Palindrome: No

Factorization: 2 ² × 5 × 13 × 83

Divisors: 1, 2, 4, 5, 10, 13, 20, 26, 52, 65

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101010001001100

Octal: 52114

Duodecimal: 105A4

Hexadecimal: 544c

Square: 465696400

Square Root: 146.90132742763083

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 binary trees with n edges and k jumps (n >= 0, 0 <= k <= max(0,ceiling(n/2)-1) ). A127530

a(n) is the smallest integer k such that sigma₂(k) = sigma₂(k + 2n), where sigma₂(k) is the sum of squares of divisors of k (A001157). A175199

Triangle read by rows: T(n,k) is the number of polygons formed by connecting the vertices of a regular 2n-gon such that the winding number around the center is k and with no side passing through the center. A343369

a(n) = 25·2ⁿ⁺³ - (198+392·n/3+36·n²+10·n³/3). A169833

Decimal expansion of 1/576. A21580