Properties of the Number 644

Six Hundred Forty-Four

Basics

Value: 643 → 644 → 645

Parity: even

Prime: No

Previous Prime: 643

Next Prime: 647

Digit Sum: 14

Digital Root: 5

Palindrome: No

Factorization: 2 ² × 7 × 23

Divisors: 1, 2, 4, 7, 14, 23, 28, 46, 92, 161

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1010000100

Octal: 1204

Duodecimal: 458

Hexadecimal: 284

Square: 414736

Square Root: 25.37715508089904

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

Perrin sequence (or Perrin numbers, or Ondrej Such sequence): a(n) = a(n-2) + a(n-3) with a(0) = 3, a(1) = 0, a(2) = 2. A1608

Number of integer partitions of n whose smallest part is equal to the number of parts. A6141

Number of partitions of n into parts having a common factor. A18783

Primitive abundant numbers: abundant numbers (A005101) having no abundant proper divisor. A91191

Palindromes in base 3 (written in base 10). A14190

Admirable numbers. A number n is admirable if there exists a proper divisor d' of n such that σ(n)-2d'=2n, where σ(n) is the sum of all divisors of n. A111592

Numbers that are the sum of 5 positive 4th powers. A3339

Number of strict integer partitions of n with no adjacent parts having quotient >= 2. A342097

a(n) = n*(n+5). A28557

Numbers k such that 2·3^k - 1 is prime. A3307