991161212790 has 32 divisors (see below), whose sum is σ = 2718613612800. Its totient is φ = 226551134304.

The previous prime is 991161212777. The next prime is 991161212843. The reversal of 991161212790 is 97212161199.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2359907440 + ... + 2359907859.

It is an arithmetic number, because the mean of its divisors is an integer number (84956675400).

Almost surely, 2^991161212790 is an apocalyptic number.

991161212790 is an abundant number, since it is smaller than the sum of its proper divisors (1727452400010).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991161212790 is a wasteful number, since it uses less digits than its factorization.

991161212790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4719815316.

The product of its (nonzero) digits is 122472, while the sum is 48.

The spelling of 991161212790 in words is "nine hundred ninety-one billion, one hundred sixty-one million, two hundred twelve thousand, seven hundred ninety".