99999999991808 has 112 divisors (see below), whose sum is σ = 228583165286400. Its totient is φ = 42852326178816.

The previous prime is 99999999991807. The next prime is 99999999991831. The reversal of 99999999991808 is 80819999999999.

It is a tau number, because it is divible by the number of its divisors (112).

It is a junction number, because it is equal to n+sod(n) for n = 99999999991696 and 99999999991705.

It is not an unprimeable number, because it can be changed into a prime (99999999991807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 535671668 + ... + 535858316.

Almost surely, 2^{99999999991808} 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 99999999991808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114291582643200).

99999999991808 is an abundant number, since it is smaller than the sum of its proper divisors (128583165294592).

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

99999999991808 is an equidigital number, since it uses as much as digits as its factorization.

99999999991808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196025 (or 196001 counting only the distinct ones).

The product of its (nonzero) digits is 223154201664, while the sum is 107.

The spelling of 99999999991808 in words is "ninety-nine trillion, nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-one thousand, eight hundred eight".