643698864 has 60 divisors (see below), whose sum is σ = 1823201016. Its totient is φ = 211977216.

The previous prime is 643698859. The next prime is 643698883. The reversal of 643698864 is 468896346.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 643698864.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14977 + ... + 38880.

Almost surely, 2^643698864 is an apocalyptic number.

It is an amenable number.

643698864 is an abundant number, since it is smaller than the sum of its proper divisors (1179502152).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

643698864 is a wasteful number, since it uses less digits than its factorization.

643698864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53954 (or 53945 counting only the distinct ones).

The product of its digits is 5971968, while the sum is 54.

The square root of 643698864 is about 25371.2211767585. The cubic root of 643698864 is about 863.4308880716.

The spelling of 643698864 in words is "six hundred forty-three million, six hundred ninety-eight thousand, eight hundred sixty-four".