991111090001 has 32 divisors (see below), whose sum is σ = 1115782536960. Its totient is φ = 874810699776.

The previous prime is 991111089971. The next prime is 991111090027. The reversal of 991111090001 is 100090111199.

991111090001 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 991111090001 - 2²² = 991106895697 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 991111090001.

It is not an unprimeable number, because it can be changed into a prime (991111690001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 154930535 + ... + 154936931.

It is an arithmetic number, because the mean of its divisors is an integer number (34868204280).

Almost surely, 2^991111090001 is an apocalyptic number.

It is an amenable number.

991111090001 is a deficient number, since it is larger than the sum of its proper divisors (124671446959).

991111090001 is a wasteful number, since it uses less digits than its factorization.

991111090001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11193.

The product of its (nonzero) digits is 729, while the sum is 32.

The spelling of 991111090001 in words is "nine hundred ninety-one billion, one hundred eleven million, ninety thousand, one".