138640872 has 64 divisors (see below), whose sum is σ = 380736000. Its totient is φ = 41874624.

The previous prime is 138640871. The next prime is 138640883. The reversal of 138640872 is 278046831.

138640872 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 138640872.

It is not an unprimeable number, because it can be changed into a prime (138640871) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3879 + ... + 17097.

It is an arithmetic number, because the mean of its divisors is an integer number (5949000).

Almost surely, 2^138640872 is an apocalyptic number.

138640872 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 138640872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (190368000).

138640872 is an abundant number, since it is smaller than the sum of its proper divisors (242095128).

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

138640872 is a wasteful number, since it uses less digits than its factorization.

138640872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13270 (or 13266 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 39.

The square root of 138640872 is about 11774.5858525895. The cubic root of 138640872 is about 517.5636421998.

The spelling of 138640872 in words is "one hundred thirty-eight million, six hundred forty thousand, eight hundred seventy-two".