991033661811 has 8 divisors (see below), whose sum is σ = 1334207130880. Its totient is φ = 654274650312.

The previous prime is 991033661791. The next prime is 991033661837. The reversal of 991033661811 is 118166330199.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 991033661811 - 2¹⁰ = 991033660787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991033661881) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1603614031 + ... + 1603614648.

It is an arithmetic number, because the mean of its divisors is an integer number (166775891360).

Almost surely, 2^991033661811 is an apocalyptic number.

991033661811 is a deficient number, since it is larger than the sum of its proper divisors (343173469069).

991033661811 is a wasteful number, since it uses less digits than its factorization.

991033661811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3207228785.

The product of its (nonzero) digits is 209952, while the sum is 48.

The spelling of 991033661811 in words is "nine hundred ninety-one billion, thirty-three million, six hundred sixty-one thousand, eight hundred eleven".