638407380808 has 8 divisors (see below), whose sum is σ = 1197013839030. Its totient is φ = 319203690400.

The previous prime is 638407380773. The next prime is 638407380883. The reversal of 638407380808 is 808083704836.

It can be written as a sum of positive squares in only one way, i.e., 366196840164 + 272210540644 = 605142^2 + 521738^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39900461293 + ... + 39900461308.

Almost surely, 2^638407380808 is an apocalyptic number.

It is an amenable number.

638407380808 is a deficient number, since it is larger than the sum of its proper divisors (558606458222).

638407380808 is a wasteful number, since it uses less digits than its factorization.

638407380808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79800922607 (or 79800922603 counting only the distinct ones).

The product of its (nonzero) digits is 6193152, while the sum is 55.

The spelling of 638407380808 in words is "six hundred thirty-eight billion, four hundred seven million, three hundred eighty thousand, eight hundred eight".