111809891 has 2 divisors, whose sum is σ = 111809892. Its totient is φ = 111809890.

The previous prime is 111809861. The next prime is 111809909. The reversal of 111809891 is 198908111.

It is a strong prime.

It is an emirp because it is prime and its reverse (198908111) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 111809891 - 2⁶ = 111809827 is a prime.

It is not a weakly prime, because it can be changed into another prime (111809821) 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, 55904945 + 55904946.

It is an arithmetic number, because the mean of its divisors is an integer number (55904946).

Almost surely, 2^111809891 is an apocalyptic number.

111809891 is a deficient number, since it is larger than the sum of its proper divisors (1).

111809891 is an equidigital number, since it uses as much as digits as its factorization.

111809891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 38.

The square root of 111809891 is about 10574.0196235869. The cubic root of 111809891 is about 481.7555663919.

The spelling of 111809891 in words is "one hundred eleven million, eight hundred nine thousand, eight hundred ninety-one".