Properties of the Number 21801

Twenty-One Thousand Eight Hundred One

Basics

Value: 21800 → 21801 → 21802

Parity: odd

Prime: No

Previous Prime: 21799

Next Prime: 21803

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 3 × 13 ² × 43

Divisors: 1, 3, 13, 39, 43, 129, 169, 507, 559, 1677

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101010100101001

Octal: 52451

Duodecimal: 10749

Hexadecimal: 5529

Square: 475283601

Square Root: 147.65161699080713

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

3 times 10-gonal (or decagonal) numbers: a(n) = 3·n*(4·n-3). A152767

a(n) = ∑_k=0..n binomial(2·k, k) * q(k), where q(k) is the number of partitions into distinct parts (A000009). A356270

a(n) = n*(14·n + 13). A195028

Numbers k such that (5·10^k + 37)/3 is prime. A281171

Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 98. A31596

Decimal expansion of 1/797. A21801