640918384 has 20 divisors (see below), whose sum is σ = 1243306584. Its totient is φ = 320065088.

The previous prime is 640918381. The next prime is 640918409. The reversal of 640918384 is 483819046.

It is a self number, because there is not a number n which added to its sum of digits gives 640918384.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640918381) 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, 10987 + ... + 37450.

Almost surely, 2^640918384 is an apocalyptic number.

It is an amenable number.

640918384 is a deficient number, since it is larger than the sum of its proper divisors (602388200).

640918384 is a wasteful number, since it uses less digits than its factorization.

640918384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49272 (or 49266 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 43.

The square root of 640918384 is about 25316.3659319421. The cubic root of 640918384 is about 862.1858869896.

The spelling of 640918384 in words is "six hundred forty million, nine hundred eighteen thousand, three hundred eighty-four".