999816072509 has 2 divisors, whose sum is σ = 999816072510. Its totient is φ = 999816072508.

The previous prime is 999816072487. The next prime is 999816072511. The reversal of 999816072509 is 905270618999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 928515324025 + 71300748484 = 963595^2 + 267022^2 .

It is a cyclic number.

It is not a de Polignac number, because 999816072509 - 2³² = 995521105213 is a prime.

It is a Sophie Germain prime.

Together with 999816072511, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999816072599) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499908036254 + 499908036255.

It is an arithmetic number, because the mean of its divisors is an integer number (499908036255).

Almost surely, 2^999816072509 is an apocalyptic number.

It is an amenable number.

999816072509 is a deficient number, since it is larger than the sum of its proper divisors (1).

999816072509 is an equidigital number, since it uses as much as digits as its factorization.

999816072509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 22044960, while the sum is 65.

The spelling of 999816072509 in words is "nine hundred ninety-nine billion, eight hundred sixteen million, seventy-two thousand, five hundred nine".