138639768 has 32 divisors (see below), whose sum is σ = 361670400. Its totient is φ = 44203808.

The previous prime is 138639731. The next prime is 138639779. The reversal of 138639768 is 867936831.

It is a self number, because there is not a number n which added to its sum of digits gives 138639768.

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, 125028 + ... + 126131.

It is an arithmetic number, because the mean of its divisors is an integer number (11302200).

Almost surely, 2^138639768 is an apocalyptic number.

It is an amenable number.

138639768 is an abundant number, since it is smaller than the sum of its proper divisors (223030632).

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

138639768 is a wasteful number, since it uses less digits than its factorization.

138639768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251191 (or 251187 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 51.

The square root of 138639768 is about 11774.5389718664. The cubic root of 138639768 is about 517.5622684063.

The spelling of 138639768 in words is "one hundred thirty-eight million, six hundred thirty-nine thousand, seven hundred sixty-eight".