138928939 has 2 divisors, whose sum is σ = 138928940. Its totient is φ = 138928938.

The previous prime is 138928891. The next prime is 138928957. The reversal of 138928939 is 939829831.

138928939 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is an emirp because it is prime and its reverse (939829831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138928939 - 2¹¹ = 138926891 is a prime.

It is not a weakly prime, because it can be changed into another prime (138928739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69464469 + 69464470.

It is an arithmetic number, because the mean of its divisors is an integer number (69464470).

Almost surely, 2^138928939 is an apocalyptic number.

138928939 is a deficient number, since it is larger than the sum of its proper divisors (1).

138928939 is an equidigital number, since it uses as much as digits as its factorization.

138928939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 839808, while the sum is 52.

The square root of 138928939 is about 11786.8120796083. The cubic root of 138928939 is about 517.9218575446.

The spelling of 138928939 in words is "one hundred thirty-eight million, nine hundred twenty-eight thousand, nine hundred thirty-nine".