1991806319250 has 864 divisors, whose sum is σ = 6402350118528. Its totient is φ = 445618800000.

The previous prime is 1991806319249. The next prime is 1991806319267. The reversal of 1991806319250 is 529136081991.

It is an unprimeable number.

It is a polite number, since it can be written in 431 ways as a sum of consecutive naturals, for example, 6017541585 + ... + 6017541915.

It is an arithmetic number, because the mean of its divisors is an integer number (7410127452).

Almost surely, 2^{1991806319250} is an apocalyptic number.

1991806319250 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991806319250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3201175059264).

1991806319250 is an abundant number, since it is smaller than the sum of its proper divisors (4410543799278).

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

1991806319250 is a wasteful number, since it uses less digits than its factorization.

1991806319250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 461 (or 406 counting only the distinct ones).

The product of its (nonzero) digits is 1049760, while the sum is 54.

The spelling of 1991806319250 in words is "one trillion, nine hundred ninety-one billion, eight hundred six million, three hundred nineteen thousand, two hundred fifty".