991111 has 6 divisors (see below), whose sum is σ = 1089536. Its totient is φ = 900900.

The previous prime is 991091. The next prime is 991127. The reversal of 991111 is 111199.

It is not a de Polignac number, because 991111 - 2⁵ = 991079 is a prime.

It is a Duffinian number.

991111 is a modest number, since divided by 1111 gives 99 as remainder.

It is a nialpdrome in base 10.

It is a zygodrome in base 2 and base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991171) 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, 3975 + ... + 4216.

2⁹⁹¹¹¹¹ is an apocalyptic number.

991111 is a deficient number, since it is larger than the sum of its proper divisors (98425).

991111 is a wasteful number, since it uses less digits than its factorization.

991111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8213 (or 8202 counting only the distinct ones).

The product of its digits is 81, while the sum is 22.

The square root of 991111 is about 995.5455790671. The cubic root of 991111 is about 99.7028177017.

The spelling of 991111 in words is "nine hundred ninety-one thousand, one hundred eleven".