999808999 has 16 divisors (see below), whose sum is σ = 1155926016. Its totient is φ = 847044000.

The previous prime is 999808951. The next prime is 999809029.

999808999 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 999808999 - 2⁷ = 999808871 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999808699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 699924 + ... + 701350.

It is an arithmetic number, because the mean of its divisors is an integer number (72245376).

Almost surely, 2^999808999 is an apocalyptic number.

999808999 is a deficient number, since it is larger than the sum of its proper divisors (156117017).

999808999 is a wasteful number, since it uses less digits than its factorization.

999808999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2526.

The product of its (nonzero) digits is 34012224, while the sum is 70.

The square root of 999808999 is about 31619.7564664878. The cubic root of 999808999 is about 999.9363289461.

The spelling of 999808999 in words is "nine hundred ninety-nine million, eight hundred eight thousand, nine hundred ninety-nine".