638405660838 has 16 divisors (see below), whose sum is σ = 1392885078336. Its totient is φ = 193456260840.

The previous prime is 638405660819. The next prime is 638405660897. The reversal of 638405660838 is 838066504836.

It is a congruent number.

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, 4836406456 + ... + 4836406587.

It is an arithmetic number, because the mean of its divisors is an integer number (87055317396).

Almost surely, 2^638405660838 is an apocalyptic number.

638405660838 is an abundant number, since it is smaller than the sum of its proper divisors (754479417498).

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

638405660838 is a wasteful number, since it uses less digits than its factorization.

638405660838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9672813059.

The product of its (nonzero) digits is 19906560, while the sum is 57.

The spelling of 638405660838 in words is "six hundred thirty-eight billion, four hundred five million, six hundred sixty thousand, eight hundred thirty-eight".