991199109912 has 32 divisors (see below), whose sum is σ = 2703270300480. Its totient is φ = 300363366560.

The previous prime is 991199109893. The next prime is 991199109919. The reversal of 991199109912 is 219901991199.

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 polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1877270778 + ... + 1877271305.

It is an arithmetic number, because the mean of its divisors is an integer number (84477196890).

Almost surely, 2^991199109912 is an apocalyptic number.

It is an amenable number.

991199109912 is an abundant number, since it is smaller than the sum of its proper divisors (1712071190568).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991199109912 is a wasteful number, since it uses less digits than its factorization.

991199109912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3754542103 (or 3754542099 counting only the distinct ones).

The product of its (nonzero) digits is 1062882, while the sum is 60.

The spelling of 991199109912 in words is "nine hundred ninety-one billion, one hundred ninety-nine million, one hundred nine thousand, nine hundred twelve".