1991080866 has 32 divisors (see below), whose sum is σ = 4014609408. Its totient is φ = 658299600.

The previous prime is 1991080841. The next prime is 1991080933. The reversal of 1991080866 is 6680801991.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 820531 + ... + 822953.

It is an arithmetic number, because the mean of its divisors is an integer number (125456544).

Almost surely, 2^1991080866 is an apocalyptic number.

1991080866 is an abundant number, since it is smaller than the sum of its proper divisors (2023528542).

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

1991080866 is a wasteful number, since it uses less digits than its factorization.

1991080866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3486.

The product of its (nonzero) digits is 186624, while the sum is 48.

The square root of 1991080866 is about 44621.5291759482. The cubic root of 1991080866 is about 1258.0453580888.

The spelling of 1991080866 in words is "one billion, nine hundred ninety-one million, eighty thousand, eight hundred sixty-six".