9111991 has 6 divisors (see below), whose sum is σ = 10599720. Its totient is φ = 7810236.

The previous prime is 9111961. The next prime is 9112043. The reversal of 9111991 is 1991119.

9111991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 9111991 - 2⁵ = 9111959 is a prime.

It is a Duffinian number.

9111991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9111911) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 92931 + ... + 93028.

It is an arithmetic number, because the mean of its divisors is an integer number (1766620).

Almost surely, 2^9111991 is an apocalyptic number.

9111991 is a deficient number, since it is larger than the sum of its proper divisors (1487729).

9111991 is a wasteful number, since it uses less digits than its factorization.

9111991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185973 (or 185966 counting only the distinct ones).

The product of its digits is 729, while the sum is 31.

The square root of 9111991 is about 3018.6074604029. The cubic root of 9111991 is about 208.8676084382.

The spelling of 9111991 in words is "nine million, one hundred eleven thousand, nine hundred ninety-one".