991900909911 has 16 divisors (see below), whose sum is σ = 1345001886720. Its totient is φ = 650034461760.

The previous prime is 991900909897. The next prime is 991900909919. The reversal of 991900909911 is 119909009199.

It is not a de Polignac number, because 991900909911 - 2⁶ = 991900909847 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991900909919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5294211 + ... + 5478363.

It is an arithmetic number, because the mean of its divisors is an integer number (84062617920).

Almost surely, 2^991900909911 is an apocalyptic number.

991900909911 is a deficient number, since it is larger than the sum of its proper divisors (353100976809).

991900909911 is a wasteful number, since it uses less digits than its factorization.

991900909911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214646.

The product of its (nonzero) digits is 531441, while the sum is 57.

The spelling of 991900909911 in words is "nine hundred ninety-one billion, nine hundred million, nine hundred nine thousand, nine hundred eleven".