640218688 has 14 divisors (see below), whose sum is σ = 1270434086. Its totient is φ = 320109312.

The previous prime is 640218679. The next prime is 640218749. The reversal of 640218688 is 886812046.

It can be written as a sum of positive squares in only one way, i.e., 629407744 + 10810944 = 25088^2 + 3288^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5001645 + ... + 5001772.

Almost surely, 2^640218688 is an apocalyptic number.

It is an amenable number.

640218688 is a deficient number, since it is larger than the sum of its proper divisors (630215398).

640218688 is a wasteful number, since it uses less digits than its factorization.

640218688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10003429 (or 10003419 counting only the distinct ones).

The product of its (nonzero) digits is 147456, while the sum is 43.

The square root of 640218688 is about 25302.5431132920. The cubic root of 640218688 is about 861.8720208794.

The spelling of 640218688 in words is "six hundred forty million, two hundred eighteen thousand, six hundred eighty-eight".