1991056325440 has 1344 divisors, whose sum is σ = 6603209169984. Its totient is φ = 564220919808.

The previous prime is 1991056325393. The next prime is 1991056325471. The reversal of 1991056325440 is 445236501991.

It can be written as a sum of positive squares in 32 ways, for example, as 158888337664 + 1832167987776 = 398608^2 + 1353576^2 .

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 6795413934 + ... + 6795414226.

It is an arithmetic number, because the mean of its divisors is an integer number (4913102061).

Almost surely, 2^{1991056325440} is an apocalyptic number.

1991056325440 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 1991056325440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3301604584992).

1991056325440 is an abundant number, since it is smaller than the sum of its proper divisors (4612152844544).

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

1991056325440 is a wasteful number, since it uses less digits than its factorization.

1991056325440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 444 (or 427 counting only the distinct ones).

The product of its (nonzero) digits is 1166400, while the sum is 49.

The spelling of 1991056325440 in words is "one trillion, nine hundred ninety-one billion, fifty-six million, three hundred twenty-five thousand, four hundred forty".