Properties of the Number 647

Six Hundred Forty-Seven

Basics

Value: 646 → 647 → 648

Parity: odd

Prime: Yes

Previous Prime: 643

Next Prime: 653

Digit Sum: 17

Digital Root: 8

Palindrome: No

Factorization: 647

Divisors: 1, 647

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1010000111

Octal: 1207

Duodecimal: 45B

Hexadecimal: 287

Square: 418609

Square Root: 25.436194683953808

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

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

Numbers k such that 3^k - 2^k is prime. A57468

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

a(n) = 2·n² - 1. A56220

Primes whose binary representation is also the decimal representation of a prime. A65720

Primes of the form 8n+7, that is, primes congruent to -1 mod 8. A7522

Number of elements in the set {(x,y): 1 <= x,y <= n, gcd(x,y)=1}. A18805

Irregular primes: primes p such that at least one of the numerators of the Bernoulli numbers B₂, B₄, ..., B_p-3 (A000367) is divisible by p. A928

Primes of form 10n+7. A30432

Larger member p+4 of cousin primes (p, p+4). A46132