1991777795904 has 112 divisors (see below), whose sum is σ = 5678706293568. Its totient is φ = 612485787648.

The previous prime is 1991777795899. The next prime is 1991777795911. The reversal of 1991777795904 is 4095977771991.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3921484 + ... + 4400180.

It is an arithmetic number, because the mean of its divisors is an integer number (50702734764).

Almost surely, 2^{1991777795904} 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 1991777795904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2839353146784).

1991777795904 is an abundant number, since it is smaller than the sum of its proper divisors (3686928497664).

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

1991777795904 is a wasteful number, since it uses less digits than its factorization.

1991777795904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 480392 (or 480382 counting only the distinct ones).

The product of its (nonzero) digits is 315059220, while the sum is 75.

The spelling of 1991777795904 in words is "one trillion, nine hundred ninety-one billion, seven hundred seventy-seven million, seven hundred ninety-five thousand, nine hundred four".