809840309 has 2 divisors, whose sum is σ = 809840310. Its totient is φ = 809840308.

The previous prime is 809840303. The next prime is 809840347. The reversal of 809840309 is 903048908.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 796481284 + 13359025 = 28222^2 + 3655^2 .

It is a cyclic number.

It is not a de Polignac number, because 809840309 - 2¹² = 809836213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (809840303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 404920154 + 404920155.

It is an arithmetic number, because the mean of its divisors is an integer number (404920155).

Almost surely, 2^809840309 is an apocalyptic number.

It is an amenable number.

809840309 is a deficient number, since it is larger than the sum of its proper divisors (1).

809840309 is an equidigital number, since it uses as much as digits as its factorization.

809840309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 62208, while the sum is 41.

The square root of 809840309 is about 28457.6933183278. The cubic root of 809840309 is about 932.1084888629.

The spelling of 809840309 in words is "eight hundred nine million, eight hundred forty thousand, three hundred nine".