111989991 has 8 divisors (see below), whose sum is σ = 151119360. Its totient is φ = 73760312.

The previous prime is 111989963. The next prime is 111990001. The reversal of 111989991 is 199989111.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 111989991 - 2¹⁴ = 111973607 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 111989991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (111989951) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 224631 + ... + 225128.

It is an arithmetic number, because the mean of its divisors is an integer number (18889920).

Almost surely, 2^111989991 is an apocalyptic number.

111989991 is a deficient number, since it is larger than the sum of its proper divisors (39129369).

111989991 is an equidigital number, since it uses as much as digits as its factorization.

111989991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 449845.

The product of its digits is 52488, while the sum is 48.

The square root of 111989991 is about 10582.5323528917. The cubic root of 111989991 is about 482.0140934109.

The spelling of 111989991 in words is "one hundred eleven million, nine hundred eighty-nine thousand, nine hundred ninety-one".