640555208 has 32 divisors (see below), whose sum is σ = 1265544000. Its totient is φ = 303111360.

The previous prime is 640555187. The next prime is 640555241. The reversal of 640555208 is 802555046.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 228278 + ... + 231066.

It is an arithmetic number, because the mean of its divisors is an integer number (39548250).

Almost surely, 2^640555208 is an apocalyptic number.

It is an amenable number.

640555208 is a deficient number, since it is larger than the sum of its proper divisors (624988792).

640555208 is a wasteful number, since it uses less digits than its factorization.

640555208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4325 (or 4321 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 35.

The square root of 640555208 is about 25309.1921641130. The cubic root of 640555208 is about 862.0230038560.

The spelling of 640555208 in words is "six hundred forty million, five hundred fifty-five thousand, two hundred eight".