991227551111 has 4 divisors (see below), whose sum is σ = 1132831486992. Its totient is φ = 849623615232.

The previous prime is 991227551099. The next prime is 991227551179. The reversal of 991227551111 is 111155722199.

991227551111 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 991227551111 - 2⁶ = 991227551047 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 (991227551191) 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, 70801967930 + ... + 70801967943.

It is an arithmetic number, because the mean of its divisors is an integer number (283207871748).

Almost surely, 2^991227551111 is an apocalyptic number.

991227551111 is a deficient number, since it is larger than the sum of its proper divisors (141603935881).

991227551111 is a wasteful number, since it uses less digits than its factorization.

991227551111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141603935880.

The product of its digits is 56700, while the sum is 44.

The spelling of 991227551111 in words is "nine hundred ninety-one billion, two hundred twenty-seven million, five hundred fifty-one thousand, one hundred eleven".