138664957 has 4 divisors (see below), whose sum is σ = 138697596. Its totient is φ = 138632320.

The previous prime is 138664873. The next prime is 138664969. The reversal of 138664957 is 759466831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 759466831 = 23 ⋅33020297.

It can be written as a sum of positive squares in 2 ways, for example, as 49758916 + 88906041 = 7054^2 + 9429^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138664957 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 138664957.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138604957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8788 + ... + 18829.

It is an arithmetic number, because the mean of its divisors is an integer number (34674399).

Almost surely, 2^138664957 is an apocalyptic number.

It is an amenable number.

138664957 is a deficient number, since it is larger than the sum of its proper divisors (32639).

138664957 is an equidigital number, since it uses as much as digits as its factorization.

138664957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32638.

The product of its digits is 1088640, while the sum is 49.

The square root of 138664957 is about 11775.6085617687. The cubic root of 138664957 is about 517.5936112327.

The spelling of 138664957 in words is "one hundred thirty-eight million, six hundred sixty-four thousand, nine hundred fifty-seven".