9991111 has 6 divisors (see below), whose sum is σ = 10818960. Its totient is φ = 9222408.

The previous prime is 9991067. The next prime is 9991123. The reversal of 9991111 is 1111999.

It is a de Polignac number, because none of the positive numbers 2^k-9991111 is a prime.

It is a Duffinian number.

9991111 is a modest number, since divided by 1111 gives 999 as remainder.

9991111 is a lucky number.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9991141) 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 in 5 ways as a sum of consecutive naturals, for example, 29391 + ... + 29728.

It is an arithmetic number, because the mean of its divisors is an integer number (1803160).

Almost surely, 2^9991111 is an apocalyptic number.

9991111 is a deficient number, since it is larger than the sum of its proper divisors (827849).

9991111 is a wasteful number, since it uses less digits than its factorization.

9991111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59145 (or 59132 counting only the distinct ones).

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

The square root of 9991111 is about 3160.8718733919. The cubic root of 9991111 is about 215.3796141794.

The spelling of 9991111 in words is "nine million, nine hundred ninety-one thousand, one hundred eleven".