643858256 has 20 divisors (see below), whose sum is σ = 1255425972. Its totient is φ = 319877376.

The previous prime is 643858249. The next prime is 643858273. The reversal of 643858256 is 652858346.

It can be written as a sum of positive squares in 2 ways, for example, as 150307600 + 493550656 = 12260^2 + 22216^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 643858256.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 125645 + ... + 130668.

Almost surely, 2^643858256 is an apocalyptic number.

It is an amenable number.

643858256 is a deficient number, since it is larger than the sum of its proper divisors (611567716).

643858256 is a wasteful number, since it uses less digits than its factorization.

643858256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256478 (or 256472 counting only the distinct ones).

The product of its digits is 1382400, while the sum is 47.

The square root of 643858256 is about 25374.3621791761. The cubic root of 643858256 is about 863.5021494568.

The spelling of 643858256 in words is "six hundred forty-three million, eight hundred fifty-eight thousand, two hundred fifty-six".