138649939 has 2 divisors, whose sum is σ = 138649940. Its totient is φ = 138649938.

The previous prime is 138649933. The next prime is 138649963. The reversal of 138649939 is 939946831.

It is a weak prime.

It is an emirp because it is prime and its reverse (939946831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138649939 - 2⁷ = 138649811 is a prime.

It is not a weakly prime, because it can be changed into another prime (138649933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69324969 + 69324970.

It is an arithmetic number, because the mean of its divisors is an integer number (69324970).

Almost surely, 2^138649939 is an apocalyptic number.

138649939 is a deficient number, since it is larger than the sum of its proper divisors (1).

138649939 is an equidigital number, since it uses as much as digits as its factorization.

138649939 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1259712, while the sum is 52.

The square root of 138649939 is about 11774.9708704523. The cubic root of 138649939 is about 517.5749247006.

The spelling of 138649939 in words is "one hundred thirty-eight million, six hundred forty-nine thousand, nine hundred thirty-nine".