Properties of the Number 641

Six Hundred Forty-One

Basics

Value: 640 → 641 → 642

Parity: odd

Prime: Yes

Previous Prime: 631

Next Prime: 643

Digit Sum: 11

Digital Root: 2

Palindrome: No

Factorization: 641

Divisors: 1, 641

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1010000001

Octal: 1201

Duodecimal: 455

Hexadecimal: 281

Square: 410881

Square Root: 25.317977802344327

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

Lesser of twin primes. A1359

Primes of the form x² + xy + 2y², with·and y nonnegative. A106856

Sophie Germain primes p: 2p+1 is also prime. A5384

Twin primes. A1097

Ramanujan primes R_n: a(n) is the smallest number such that if x >= a(n), then π(x) - π(x/2) >= n, where π(x) is the number of primes <= x. A104272

Primes p such that p + 6 is also prime. (Lesser of a pair of sexy primes.) A23201

Primes of the form k² + k + 41. A5846

Primes of form 8n+1, that is, primes congruent to 1 mod 8. A7519

Primes of the form 10·n+1. A30430

Initial members of prime triples (p, p+2, p+6). A22004