991199109911 has 4 divisors (see below), whose sum is σ = 996230577672. Its totient is φ = 986167642152.

The previous prime is 991199109893. The next prime is 991199109919. The reversal of 991199109911 is 119901991199.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991199109911 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 (991199109919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2515733585 + ... + 2515733978.

It is an arithmetic number, because the mean of its divisors is an integer number (249057644418).

Almost surely, 2^991199109911 is an apocalyptic number.

991199109911 is a deficient number, since it is larger than the sum of its proper divisors (5031467761).

991199109911 is a wasteful number, since it uses less digits than its factorization.

991199109911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5031467760.

The product of its (nonzero) digits is 531441, while the sum is 59.

The spelling of 991199109911 in words is "nine hundred ninety-one billion, one hundred ninety-nine million, one hundred nine thousand, nine hundred eleven".