Properties of the Number 81220

Eighty-One Thousand Two Hundred Twenty

Basics

Value: 81219 → 81220 → 81221

Parity: even

Prime: No

Previous Prime: 81203

Next Prime: 81223

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 2 ² × 5 × 31 × 131

Divisors: 1, 2, 4, 5, 10, 20, 31, 62, 124, 131

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 10011110101000100

Octal: 236504

Duodecimal: 3B004

Hexadecimal: 13d44

Square: 6596688400

Square Root: 284.991227935177

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

Numbers n such that n!10-1 is prime. A204658

G.f. = b(2)*b(4)*b(6)/(x⁸+x⁶-x⁵-x³-x+1), where b(k) = (1-x^k)/(1-x). A266333

Palindromic primes = 1 mod 4. A81220