1991434765320 has 512 divisors, whose sum is σ = 8912719872000. Its totient is φ = 381973294080.

The previous prime is 1991434765319. The next prime is 1991434765357. The reversal of 1991434765320 is 235674341991.

1991434765320 is a `hidden beast` number, since 1 + 9 + 9 + 1 + 4 + 34 + 76 + 532 + 0 = 666.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 160041 + ... + 2002119.

It is an arithmetic number, because the mean of its divisors is an integer number (17407656000).

Almost surely, 2^{1991434765320} is an apocalyptic number.

1991434765320 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991434765320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4456359936000).

1991434765320 is an abundant number, since it is smaller than the sum of its proper divisors (6921285106680).

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

1991434765320 is a wasteful number, since it uses less digits than its factorization.

1991434765320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1842130 (or 1842120 counting only the distinct ones).

The product of its (nonzero) digits is 4898880, while the sum is 54.

The spelling of 1991434765320 in words is "one trillion, nine hundred ninety-one billion, four hundred thirty-four million, seven hundred sixty-five thousand, three hundred twenty".