138928 has 20 divisors (see below), whose sum is σ = 283960. Its totient is φ = 65664.

The previous prime is 138923. The next prime is 138937. The reversal of 138928 is 829831.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 138928.

It is not an unprimeable number, because it can be changed into a prime (138923) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76 + ... + 532.

It is an arithmetic number, because the mean of its divisors is an integer number (14198).

2¹³⁸⁹²⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 138928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (141980).

138928 is an abundant number, since it is smaller than the sum of its proper divisors (145032).

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

138928 is a wasteful number, since it uses less digits than its factorization.

138928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484 (or 478 counting only the distinct ones).

The product of its digits is 3456, while the sum is 31.

The square root of 138928 is about 372.7304656183. The cubic root of 138928 is about 51.7920690690.

The spelling of 138928 in words is "one hundred thirty-eight thousand, nine hundred twenty-eight".