638351980 has 24 divisors (see below), whose sum is σ = 1532045088. Its totient is φ = 218863488.

The previous prime is 638351977. The next prime is 638351993. The reversal of 638351980 is 89153836.

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, 2279689 + ... + 2279968.

It is an arithmetic number, because the mean of its divisors is an integer number (63835212).

Almost surely, 2^638351980 is an apocalyptic number.

It is an amenable number.

638351980 is an abundant number, since it is smaller than the sum of its proper divisors (893693108).

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

638351980 is a wasteful number, since it uses less digits than its factorization.

638351980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4559673 (or 4559671 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 43.

The square root of 638351980 is about 25265.6284307357. The cubic root of 638351980 is about 861.0335419672.

The spelling of 638351980 in words is "six hundred thirty-eight million, three hundred fifty-one thousand, nine hundred eighty".