640677868 has 48 divisors (see below), whose sum is σ = 1189859328. Its totient is φ = 301392000.

The previous prime is 640677859. The next prime is 640677871. The reversal of 640677868 is 868776046.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1229448 + ... + 1229968.

It is an arithmetic number, because the mean of its divisors is an integer number (24788736).

Almost surely, 2^640677868 is an apocalyptic number.

It is an amenable number.

640677868 is a deficient number, since it is larger than the sum of its proper divisors (549181460).

640677868 is a wasteful number, since it uses less digits than its factorization.

640677868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 814 (or 812 counting only the distinct ones).

The product of its (nonzero) digits is 2709504, while the sum is 52.

The square root of 640677868 is about 25311.6152783658. The cubic root of 640677868 is about 862.0780233099.

The spelling of 640677868 in words is "six hundred forty million, six hundred seventy-seven thousand, eight hundred sixty-eight".