111888991 has 4 divisors (see below), whose sum is σ = 111962592. Its totient is φ = 111815392.

The previous prime is 111888983. The next prime is 111889021. The reversal of 111888991 is 199888111.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199888111 = 887 ⋅225353.

It is a cyclic number.

It is not a de Polignac number, because 111888991 - 2³ = 111888983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (111888901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34471 + ... + 37576.

It is an arithmetic number, because the mean of its divisors is an integer number (27990648).

Almost surely, 2^111888991 is an apocalyptic number.

111888991 is a deficient number, since it is larger than the sum of its proper divisors (73601).

111888991 is an equidigital number, since it uses as much as digits as its factorization.

111888991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73600.

The product of its digits is 41472, while the sum is 46.

The square root of 111888991 is about 10577.7592617718. The cubic root of 111888991 is about 481.8691457370.

It can be divided in two parts, 1118 and 88991, that added together give a palindrome (90109).

The spelling of 111888991 in words is "one hundred eleven million, eight hundred eighty-eight thousand, nine hundred ninety-one".