138638280 has 128 divisors (see below), whose sum is σ = 457850880. Its totient is φ = 33304320.

The previous prime is 138638251. The next prime is 138638329. The reversal of 138638280 is 82836831.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 167227 + ... + 168053.

It is an arithmetic number, because the mean of its divisors is an integer number (3576960).

Almost surely, 2^138638280 is an apocalyptic number.

138638280 is a gapful number since it is divisible by the number (10) 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 138638280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (228925440).

138638280 is an abundant number, since it is smaller than the sum of its proper divisors (319212600).

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

138638280 is a wasteful number, since it uses less digits than its factorization.

138638280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 979 (or 975 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 39.

The square root of 138638280 is about 11774.4757845095. The cubic root of 138638280 is about 517.5604167601.

The spelling of 138638280 in words is "one hundred thirty-eight million, six hundred thirty-eight thousand, two hundred eighty".