138904728 has 32 divisors (see below), whose sum is σ = 362361600. Its totient is φ = 44288288.

The previous prime is 138904721. The next prime is 138904741. The reversal of 138904728 is 827409831.

It is a self number, because there is not a number n which added to its sum of digits gives 138904728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138904721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 125268 + ... + 126371.

It is an arithmetic number, because the mean of its divisors is an integer number (11323800).

Almost surely, 2^138904728 is an apocalyptic number.

It is an amenable number.

138904728 is an abundant number, since it is smaller than the sum of its proper divisors (223456872).

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

138904728 is a wasteful number, since it uses less digits than its factorization.

138904728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251671 (or 251667 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 42.

The square root of 138904728 is about 11785.7849971905. The cubic root of 138904728 is about 517.8917698977.

The spelling of 138904728 in words is "one hundred thirty-eight million, nine hundred four thousand, seven hundred twenty-eight".