1991878785160 has 64 divisors (see below), whose sum is σ = 5046871795200. Its totient is φ = 700954406400.

The previous prime is 1991878785139. The next prime is 1991878785161. The reversal of 1991878785160 is 615878781991.

It is a self number, because there is not a number n which added to its sum of digits gives 1991878785160.

It is not an unprimeable number, because it can be changed into a prime (1991878785161) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 73002445 + ... + 73029724.

It is an arithmetic number, because the mean of its divisors is an integer number (78857371800).

Almost surely, 2^{1991878785160} is an apocalyptic number.

1991878785160 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1991878785160 is an abundant number, since it is smaller than the sum of its proper divisors (3054993010040).

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

1991878785160 is a wasteful number, since it uses less digits than its factorization.

1991878785160 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146032222 (or 146032218 counting only the distinct ones).

The product of its (nonzero) digits is 60963840, while the sum is 70.

The spelling of 1991878785160 in words is "one trillion, nine hundred ninety-one billion, eight hundred seventy-eight million, seven hundred eighty-five thousand, one hundred sixty".