138639173 has 2 divisors, whose sum is σ = 138639174. Its totient is φ = 138639172.

The previous prime is 138639157. The next prime is 138639187. The reversal of 138639173 is 371936831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 137194369 + 1444804 = 11713^2 + 1202^2 .

It is a cyclic number.

It is not a de Polignac number, because 138639173 - 2⁴ = 138639157 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 138639173.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138639113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69319586 + 69319587.

It is an arithmetic number, because the mean of its divisors is an integer number (69319587).

Almost surely, 2^138639173 is an apocalyptic number.

It is an amenable number.

138639173 is a deficient number, since it is larger than the sum of its proper divisors (1).

138639173 is an equidigital number, since it uses as much as digits as its factorization.

138639173 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81648, while the sum is 41.

The square root of 138639173 is about 11774.5137054572. The cubic root of 138639173 is about 517.5615279983.

The spelling of 138639173 in words is "one hundred thirty-eight million, six hundred thirty-nine thousand, one hundred seventy-three".