999000809 has 2 divisors, whose sum is σ = 999000810. Its totient is φ = 999000808.

The previous prime is 999000773. The next prime is 999000817. The reversal of 999000809 is 908000999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 549433600 + 449567209 = 23440^2 + 21203^2 .

It is a cyclic number.

It is not a de Polignac number, because 999000809 - 2²⁰ = 997952233 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 999000809.

It is not a weakly prime, because it can be changed into another prime (999003809) 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 as a sum of consecutive naturals, namely, 499500404 + 499500405.

It is an arithmetic number, because the mean of its divisors is an integer number (499500405).

Almost surely, 2^999000809 is an apocalyptic number.

It is an amenable number.

999000809 is a deficient number, since it is larger than the sum of its proper divisors (1).

999000809 is an equidigital number, since it uses as much as digits as its factorization.

999000809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 52488, while the sum is 44.

The square root of 999000809 is about 31606.9740563693. The cubic root of 999000809 is about 999.6668253403. Note that the first 3 decimals are identical.

The spelling of 999000809 in words is "nine hundred ninety-nine million, eight hundred nine", and thus it is an aban number.