Properties of the Number -644

Six Hundred Forty-Four

Basics

Value: -645 → -644 → -643

Parity: even

Prime: No

Previous Prime:

Next Prime: 1

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

a(n) = -2·n² + 12·n - 14. A147973

a(n) = [xⁿ] ∏_k>=1 ((1 + x^2·k-1)/(1 + x^2·k))ⁿ. A296043

A Somos-4 variant: a(n) = (36·a(n-1)*a(n-3) - 68·a(n-2)²)/a(n-4). A162546

Coefficients in the expansion of B⁷/C, in Watson's notation of page 118. A160534

Start with 1, add the next number if one gets a prime then add the next number else subtract the next... A74170

a(n) = det M_n where M_n is the n X n matrix m(i,j) = A000041(i+j). A278838

Matrix inverse of triangle A055340(n+1,k). A55347

A355906(n)/3. A355907

Counterclockwise square spiral constructed using the integers so that a(n) plus all other numbers currently visible from the current number equals n; start with a(0) = 0. A357985

First differences of number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 390", based on the 5-celled von Neumann neighborhood. A271601