19991010816 has 640 divisors, whose sum is σ = 72595353600. Its totient is φ = 5305098240.

The previous prime is 19991010779. The next prime is 19991010833. The reversal of 19991010816 is 61801019991.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 152603071 + ... + 152603201.

It is an arithmetic number, because the mean of its divisors is an integer number (113430240).

Almost surely, 2^19991010816 is an apocalyptic number.

19991010816 is a gapful number since it is divisible by the number (16) 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 19991010816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36297676800).

19991010816 is an abundant number, since it is smaller than the sum of its proper divisors (52604342784).

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

19991010816 is a wasteful number, since it uses less digits than its factorization.

19991010816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267 (or 245 counting only the distinct ones).

The product of its (nonzero) digits is 34992, while the sum is 45.

The spelling of 19991010816 in words is "nineteen billion, nine hundred ninety-one million, ten thousand, eight hundred sixteen".