999815009 has 2 divisors, whose sum is σ = 999815010. Its totient is φ = 999815008.

The previous prime is 999814967. The next prime is 999815027. The reversal of 999815009 is 900518999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 837813025 + 162001984 = 28945^2 + 12728^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-999815009 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (999815029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499907504 + 499907505.

It is an arithmetic number, because the mean of its divisors is an integer number (499907505).

Almost surely, 2^999815009 is an apocalyptic number.

It is an amenable number.

999815009 is a deficient number, since it is larger than the sum of its proper divisors (1).

999815009 is an equidigital number, since it uses as much as digits as its factorization.

999815009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 262440, while the sum is 50.

The square root of 999815009 is about 31619.8515018651. The cubic root of 999815009 is about 999.9383325305.

The spelling of 999815009 in words is "nine hundred ninety-nine million, eight hundred fifteen thousand, nine".