19999799820 has 864 divisors, whose sum is σ = 84262441536. Its totient is φ = 3773952000.

The previous prime is 19999799759. The next prime is 19999799837. The reversal of 19999799820 is 2899799991.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 127387182 + ... + 127387338.

It is an arithmetic number, because the mean of its divisors is an integer number (97525974).

Almost surely, 2^19999799820 is an apocalyptic number.

19999799820 is a gapful number since it is divisible by the number (10) 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 19999799820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42131220768).

19999799820 is an abundant number, since it is smaller than the sum of its proper divisors (64262641716).

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

19999799820 is a wasteful number, since it uses less digits than its factorization.

19999799820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311 (or 299 counting only the distinct ones).

The product of its (nonzero) digits is 59521392, while the sum is 72.

The spelling of 19999799820 in words is "nineteen billion, nine hundred ninety-nine million, seven hundred ninety-nine thousand, eight hundred twenty".