138691871 has 2 divisors, whose sum is σ = 138691872. Its totient is φ = 138691870.

The previous prime is 138691841. The next prime is 138691879. The reversal of 138691871 is 178196831.

It is a strong prime.

It is an emirp because it is prime and its reverse (178196831) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138691871 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138691879) 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, 69345935 + 69345936.

It is an arithmetic number, because the mean of its divisors is an integer number (69345936).

Almost surely, 2^138691871 is an apocalyptic number.

138691871 is a deficient number, since it is larger than the sum of its proper divisors (1).

138691871 is an equidigital number, since it uses as much as digits as its factorization.

138691871 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 44.

The square root of 138691871 is about 11776.7512922707. The cubic root of 138691871 is about 517.6270962928.

The spelling of 138691871 in words is "one hundred thirty-eight million, six hundred ninety-one thousand, eight hundred seventy-one".