111111391 has 2 divisors, whose sum is σ = 111111392. Its totient is φ = 111111390.

The previous prime is 111111361. The next prime is 111111397. The reversal of 111111391 is 193111111.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (193111111) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 111111391 - 2⁵ = 111111359 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111111397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55555695 + 55555696.

It is an arithmetic number, because the mean of its divisors is an integer number (55555696).

Almost surely, 2^111111391 is an apocalyptic number.

111111391 is a deficient number, since it is larger than the sum of its proper divisors (1).

111111391 is an equidigital number, since it uses as much as digits as its factorization.

111111391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27, while the sum is 19.

The square root of 111111391 is about 10540.9388101819. The cubic root of 111111391 is about 480.7502604384.

The spelling of 111111391 in words is "one hundred eleven million, one hundred eleven thousand, three hundred ninety-one".