191912810991 has 16 divisors (see below), whose sum is σ = 282282382080. Its totient is φ = 115003929920.

The previous prime is 191912810987. The next prime is 191912811023. The reversal of 191912810991 is 199018219191.

It is a happy number.

It is not a de Polignac number, because 191912810991 - 2² = 191912810987 is a prime.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191912811991) 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, 32668635 + ... + 32674508.

It is an arithmetic number, because the mean of its divisors is an integer number (17642648880).

Almost surely, 2^191912810991 is an apocalyptic number.

191912810991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

191912810991 is a deficient number, since it is larger than the sum of its proper divisors (90369571089).

191912810991 is a wasteful number, since it uses less digits than its factorization.

191912810991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65343246.

The product of its (nonzero) digits is 104976, while the sum is 51.

The spelling of 191912810991 in words is "one hundred ninety-one billion, nine hundred twelve million, eight hundred ten thousand, nine hundred ninety-one".