10891198991 has 2 divisors, whose sum is σ = 10891198992. Its totient is φ = 10891198990.

The previous prime is 10891198979. The next prime is 10891199017. The reversal of 10891198991 is 19989119801.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-10891198991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (10891198921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5445599495 + 5445599496.

It is an arithmetic number, because the mean of its divisors is an integer number (5445599496).

Almost surely, 2^10891198991 is an apocalyptic number.

10891198991 is a deficient number, since it is larger than the sum of its proper divisors (1).

10891198991 is an equidigital number, since it uses as much as digits as its factorization.

10891198991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 419904, while the sum is 56.

The spelling of 10891198991 in words is "ten billion, eight hundred ninety-one million, one hundred ninety-eight thousand, nine hundred ninety-one".