640139980 has 24 divisors (see below), whose sum is σ = 1345120560. Its totient is φ = 255898560.

The previous prime is 640139893. The next prime is 640139999. The reversal of 640139980 is 89931046.

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, 26835 + ... + 44725.

It is an arithmetic number, because the mean of its divisors is an integer number (56046690).

Almost surely, 2^640139980 is an apocalyptic number.

It is an amenable number.

640139980 is an abundant number, since it is smaller than the sum of its proper divisors (704980580).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640139980 is a wasteful number, since it uses less digits than its factorization.

640139980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19689 (or 19687 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 640139980 is about 25300.9877277548. The cubic root of 640139980 is about 861.8367001344.

The spelling of 640139980 in words is "six hundred forty million, one hundred thirty-nine thousand, nine hundred eighty".