1991401489792 has 288 divisors, whose sum is σ = 4733183911680. Its totient is φ = 833564160000.

The previous prime is 1991401489697. The next prime is 1991401489837. The reversal of 1991401489792 is 2979841041991.

It is a Harshad number since it is a multiple of its sum of digits (64).

It is a congruent number.

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 35 ways as a sum of consecutive naturals, for example, 1730148417 + ... + 1730149567.

It is an arithmetic number, because the mean of its divisors is an integer number (16434666360).

Almost surely, 2^{1991401489792} 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 1991401489792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2366591955840).

1991401489792 is an abundant number, since it is smaller than the sum of its proper divisors (2741782421888).

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

1991401489792 is a wasteful number, since it uses less digits than its factorization.

1991401489792 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1874 (or 1838 counting only the distinct ones).

The product of its (nonzero) digits is 11757312, while the sum is 64.

The spelling of 1991401489792 in words is "one trillion, nine hundred ninety-one billion, four hundred one million, four hundred eighty-nine thousand, seven hundred ninety-two".