1991306810784 has 192 divisors, whose sum is σ = 5731042947840. Its totient is φ = 602598850560.

The previous prime is 1991306810777. The next prime is 1991306810849. The reversal of 1991306810784 is 4870186031991.

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 31 ways as a sum of consecutive naturals, for example, 50289874 + ... + 50329454.

It is an arithmetic number, because the mean of its divisors is an integer number (29849182020).

Almost surely, 2^{1991306810784} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991306810784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2865521473920).

1991306810784 is an abundant number, since it is smaller than the sum of its proper divisors (3739736137056).

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

1991306810784 is a wasteful number, since it uses less digits than its factorization.

1991306810784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40703 (or 40695 counting only the distinct ones).

The product of its (nonzero) digits is 2612736, while the sum is 57.

The spelling of 1991306810784 in words is "one trillion, nine hundred ninety-one billion, three hundred six million, eight hundred ten thousand, seven hundred eighty-four".