Properties of the Number 643

Six Hundred Forty-Three

Basics

Value: 642 → 643 → 644

Parity: odd

Prime: Yes

Previous Prime: 641

Next Prime: 647

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 643

Divisors: 1, 643

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1010000011

Octal: 1203

Duodecimal: 457

Hexadecimal: 283

Square: 413449

Square Root: 25.357444666211933

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

Greater of twin primes. A6512

Twin primes. A1097

Primes p such that p + 4 is also prime. A23200

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

Primes such that their decimal representations interpreted in base 11 are also prime. A91924

Primes of form 10n+3. A30431

Primes whose decimal representation is a valid number in base 8 and interpreted as such is again a prime. A235394

Fortunate numbers: least m > 1 such that m + prime(n)# is prime, where p# denotes the product of all primes <= p. A5235

Numbers whose binary expansion is a decimal prime. A36952