991291056911 has 4 divisors (see below), whose sum is σ = 999096498432. Its totient is φ = 983485615392.

The previous prime is 991291056893. The next prime is 991291056913. The reversal of 991291056911 is 119650192199.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 991291056911 - 2³⁴ = 974111187727 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 (991291056913) 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, 3902720570 + ... + 3902720823.

It is an arithmetic number, because the mean of its divisors is an integer number (249774124608).

Almost surely, 2^991291056911 is an apocalyptic number.

991291056911 is a deficient number, since it is larger than the sum of its proper divisors (7805441521).

991291056911 is a wasteful number, since it uses less digits than its factorization.

991291056911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7805441520.

The product of its (nonzero) digits is 393660, while the sum is 53.

The spelling of 991291056911 in words is "nine hundred ninety-one billion, two hundred ninety-one million, fifty-six thousand, nine hundred eleven".