10911801991 has 4 divisors (see below), whose sum is σ = 11165564872. Its totient is φ = 10658039112.

The previous prime is 10911801937. The next prime is 10911802007. The reversal of 10911801991 is 19910811901.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19910811901 = 73877 ⋅269513.

It is a cyclic number.

It is not a de Polignac number, because 10911801991 - 2⁷ = 10911801863 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 (10911801391) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 126881376 + ... + 126881461.

It is an arithmetic number, because the mean of its divisors is an integer number (2791391218).

Almost surely, 2^10911801991 is an apocalyptic number.

10911801991 is a deficient number, since it is larger than the sum of its proper divisors (253762881).

10911801991 is an equidigital number, since it uses as much as digits as its factorization.

10911801991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 253762880.

The product of its (nonzero) digits is 5832, while the sum is 40.

The spelling of 10911801991 in words is "ten billion, nine hundred eleven million, eight hundred one thousand, nine hundred ninety-one".