138628891 has 2 divisors, whose sum is σ = 138628892. Its totient is φ = 138628890.

The previous prime is 138628873. The next prime is 138628901. The reversal of 138628891 is 198826831.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 138628891 - 2⁵ = 138628859 is a prime.

It is not a weakly prime, because it can be changed into another prime (138628801) 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, 69314445 + 69314446.

It is an arithmetic number, because the mean of its divisors is an integer number (69314446).

Almost surely, 2^138628891 is an apocalyptic number.

138628891 is a deficient number, since it is larger than the sum of its proper divisors (1).

138628891 is an equidigital number, since it uses as much as digits as its factorization.

138628891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 165888, while the sum is 46.

The square root of 138628891 is about 11774.0770763572. The cubic root of 138628891 is about 517.5487329153.

The spelling of 138628891 in words is "one hundred thirty-eight million, six hundred twenty-eight thousand, eight hundred ninety-one".