138928891 has 2 divisors, whose sum is σ = 138928892. Its totient is φ = 138928890.

The previous prime is 138928883. The next prime is 138928939. The reversal of 138928891 is 198829831.

It is a weak prime.

It is an emirp because it is prime and its reverse (198829831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138928891 - 2³ = 138928883 is a prime.

It is not a weakly prime, because it can be changed into another prime (138928831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69464445 + 69464446.

It is an arithmetic number, because the mean of its divisors is an integer number (69464446).

Almost surely, 2^138928891 is an apocalyptic number.

138928891 is a deficient number, since it is larger than the sum of its proper divisors (1).

138928891 is an equidigital number, since it uses as much as digits as its factorization.

138928891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 248832, while the sum is 49.

The square root of 138928891 is about 11786.8100434341. The cubic root of 138928891 is about 517.9217978972.

The spelling of 138928891 in words is "one hundred thirty-eight million, nine hundred twenty-eight thousand, eight hundred ninety-one".