138631897 has 2 divisors, whose sum is σ = 138631898. Its totient is φ = 138631896.

The previous prime is 138631873. The next prime is 138631901. The reversal of 138631897 is 798136831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 106584976 + 32046921 = 10324^2 + 5661^2 .

It is an emirp because it is prime and its reverse (798136831) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138631897 is a prime.

It is not a weakly prime, because it can be changed into another prime (138631837) 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, 69315948 + 69315949.

It is an arithmetic number, because the mean of its divisors is an integer number (69315949).

Almost surely, 2^138631897 is an apocalyptic number.

It is an amenable number.

138631897 is a deficient number, since it is larger than the sum of its proper divisors (1).

138631897 is an equidigital number, since it uses as much as digits as its factorization.

138631897 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 46.

The square root of 138631897 is about 11774.2047289828. The cubic root of 138631897 is about 517.5524736945.

The spelling of 138631897 in words is "one hundred thirty-eight million, six hundred thirty-one thousand, eight hundred ninety-seven".