138655817 has 2 divisors, whose sum is σ = 138655818. Its totient is φ = 138655816.

The previous prime is 138655813. The next prime is 138655831. The reversal of 138655817 is 718556831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 95043001 + 43612816 = 9749^2 + 6604^2 .

It is an emirp because it is prime and its reverse (718556831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138655817 - 2² = 138655813 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (138655813) 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, 69327908 + 69327909.

It is an arithmetic number, because the mean of its divisors is an integer number (69327909).

Almost surely, 2^138655817 is an apocalyptic number.

It is an amenable number.

138655817 is a deficient number, since it is larger than the sum of its proper divisors (1).

138655817 is an equidigital number, since it uses as much as digits as its factorization.

138655817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 201600, while the sum is 44.

The square root of 138655817 is about 11775.2204650274. The cubic root of 138655817 is about 517.5822387137.

The spelling of 138655817 in words is "one hundred thirty-eight million, six hundred fifty-five thousand, eight hundred seventeen".