643931051 has 4 divisors (see below), whose sum is σ = 666135600. Its totient is φ = 621726504.

The previous prime is 643931027. The next prime is 643931053. The reversal of 643931051 is 150139346.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 643931051 - 2²⁶ = 576822187 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643930999 and 643931017.

It is not an unprimeable number, because it can be changed into a prime (643931053) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11102231 + ... + 11102288.

It is an arithmetic number, because the mean of its divisors is an integer number (166533900).

Almost surely, 2^643931051 is an apocalyptic number.

643931051 is a deficient number, since it is larger than the sum of its proper divisors (22204549).

643931051 is a wasteful number, since it uses less digits than its factorization.

643931051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22204548.

The product of its (nonzero) digits is 9720, while the sum is 32.

The square root of 643931051 is about 25375.7965589260. The cubic root of 643931051 is about 863.5346909205.

The spelling of 643931051 in words is "six hundred forty-three million, nine hundred thirty-one thousand, fifty-one".