138439128 has 32 divisors (see below), whose sum is σ = 347636160. Its totient is φ = 45941280.

The previous prime is 138439121. The next prime is 138439129. The reversal of 138439128 is 821934831.

It is a super-2 number, since 2×138439128² = 38330784322800768, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138439121) 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, 7258 + ... + 18153.

It is an arithmetic number, because the mean of its divisors is an integer number (10863630).

Almost surely, 2^138439128 is an apocalyptic number.

It is an amenable number.

138439128 is an abundant number, since it is smaller than the sum of its proper divisors (209197032).

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

138439128 is a wasteful number, since it uses less digits than its factorization.

138439128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25647 (or 25643 counting only the distinct ones).

The product of its digits is 41472, while the sum is 39.

The square root of 138439128 is about 11766.0158082505. The cubic root of 138439128 is about 517.3124751720.

The spelling of 138439128 in words is "one hundred thirty-eight million, four hundred thirty-nine thousand, one hundred twenty-eight".