991112111 has 4 divisors (see below), whose sum is σ = 1081213224. Its totient is φ = 901011000.

The previous prime is 991112107. The next prime is 991112119. The reversal of 991112111 is 111211199.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 991112111 - 2² = 991112107 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 (991112119) 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, 45050540 + ... + 45050561.

It is an arithmetic number, because the mean of its divisors is an integer number (270303306).

Almost surely, 2^991112111 is an apocalyptic number.

991112111 is a deficient number, since it is larger than the sum of its proper divisors (90101113).

991112111 is a wasteful number, since it uses less digits than its factorization.

991112111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90101112.

The product of its digits is 162, while the sum is 26.

The square root of 991112111 is about 31481.9330886780. The cubic root of 991112111 is about 997.0285495611.

It can be divided in two parts, 9911 and 12111, that added together give a palindrome (22022).

The spelling of 991112111 in words is "nine hundred ninety-one million, one hundred twelve thousand, one hundred eleven".