1991715816 has 64 divisors (see below), whose sum is σ = 5040705600. Its totient is φ = 655769088.

The previous prime is 1991715811. The next prime is 1991715823. The reversal of 1991715816 is 6185171991.

It is not an unprimeable number, because it can be changed into a prime (1991715811) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 672996 + ... + 675948.

It is an arithmetic number, because the mean of its divisors is an integer number (78761025).

Almost surely, 2^1991715816 is an apocalyptic number.

It is an amenable number.

1991715816 is an abundant number, since it is smaller than the sum of its proper divisors (3048989784).

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

1991715816 is a wasteful number, since it uses less digits than its factorization.

1991715816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3298 (or 3294 counting only the distinct ones).

The product of its digits is 136080, while the sum is 48.

The square root of 1991715816 is about 44628.6434479024. The cubic root of 1991715816 is about 1258.1790728996.

The spelling of 1991715816 in words is "one billion, nine hundred ninety-one million, seven hundred fifteen thousand, eight hundred sixteen".