999999999808 has 28 divisors (see below), whose sum is σ = 1985656264900. Its totient is φ = 499677161472.

The previous prime is 999999999767. The next prime is 999999999847. The reversal of 999999999808 is 808999999999.

It can be written as a sum of positive squares in 2 ways, for example, as 641716349184 + 358283650624 = 801072^2 + 598568^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 999999999808.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 4944441 + ... + 5142712.

It is an arithmetic number, because the mean of its divisors is an integer number (70916295175).

Almost surely, 2^999999999808 is an apocalyptic number.

It is an amenable number.

999999999808 is a deficient number, since it is larger than the sum of its proper divisors (985656265092).

999999999808 is a wasteful number, since it uses less digits than its factorization.

999999999808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10088714 (or 10088704 counting only the distinct ones).

The product of its (nonzero) digits is 24794911296, while the sum is 97.

The spelling of 999999999808 in words is "nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred eight".