138520939 has 2 divisors, whose sum is σ = 138520940. Its totient is φ = 138520938.

The previous prime is 138520909. The next prime is 138520957. The reversal of 138520939 is 939025831.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138520939 is a prime.

It is not a weakly prime, because it can be changed into another prime (138520909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69260469 + 69260470.

It is an arithmetic number, because the mean of its divisors is an integer number (69260470).

Almost surely, 2^138520939 is an apocalyptic number.

138520939 is a deficient number, since it is larger than the sum of its proper divisors (1).

138520939 is an equidigital number, since it uses as much as digits as its factorization.

138520939 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 58320, while the sum is 40.

The square root of 138520939 is about 11769.4918751831. The cubic root of 138520939 is about 517.4143575360.

The spelling of 138520939 in words is "one hundred thirty-eight million, five hundred twenty thousand, nine hundred thirty-nine".