640655884 has 24 divisors (see below), whose sum is σ = 1239830928. Its totient is φ = 287216640.

The previous prime is 640655881. The next prime is 640655887. The reversal of 640655884 is 488556046.

It is an interprime number because it is at equal distance from previous prime (640655881) and next prime (640655887).

It is not an unprimeable number, because it can be changed into a prime (640655881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 96517 + ... + 102940.

It is an arithmetic number, because the mean of its divisors is an integer number (51659622).

Almost surely, 2^640655884 is an apocalyptic number.

It is an amenable number.

640655884 is a deficient number, since it is larger than the sum of its proper divisors (599175044).

640655884 is a wasteful number, since it uses less digits than its factorization.

640655884 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199545 (or 199543 counting only the distinct ones).

The product of its (nonzero) digits is 921600, while the sum is 46.

The square root of 640655884 is about 25311.1810076101. The cubic root of 640655884 is about 862.0681628475.

The spelling of 640655884 in words is "six hundred forty million, six hundred fifty-five thousand, eight hundred eighty-four".