138978 has 24 divisors (see below), whose sum is σ = 344448. Its totient is φ = 39672.

The previous prime is 138977. The next prime is 139021. The reversal of 138978 is 879831.

138978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (138977) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 426 + ... + 677.

It is an arithmetic number, because the mean of its divisors is an integer number (14352).

2¹³⁸⁹⁷⁸ is an apocalyptic number.

138978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

138978 is an abundant number, since it is smaller than the sum of its proper divisors (205470).

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

138978 is a wasteful number, since it uses less digits than its factorization.

138978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1118 (or 1115 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 138978 is about 372.7975321807. The cubic root of 138978 is about 51.7982816224.

The spelling of 138978 in words is "one hundred thirty-eight thousand, nine hundred seventy-eight".