991201220111 has 6 divisors (see below), whose sum is σ = 1046115415512. Its totient is φ = 939032734500.

The previous prime is 991201220047. The next prime is 991201220143. The reversal of 991201220111 is 111022102199.

It is not a de Polignac number, because 991201220111 - 2⁶ = 991201220047 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 (991251220111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1372854515 + ... + 1372855236.

It is an arithmetic number, because the mean of its divisors is an integer number (174352569252).

Almost surely, 2^991201220111 is an apocalyptic number.

991201220111 is a deficient number, since it is larger than the sum of its proper divisors (54914195401).

991201220111 is a wasteful number, since it uses less digits than its factorization.

991201220111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2745709789 (or 2745709770 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 29.

The spelling of 991201220111 in words is "nine hundred ninety-one billion, two hundred one million, two hundred twenty thousand, one hundred eleven".