509909 has 2 divisors, whose sum is σ = 509910. Its totient is φ = 509908.

The previous prime is 509879. The next prime is 509911. The reversal of 509909 is 909905.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 448900 + 61009 = 670^2 + 247^2 .

It is a cyclic number.

It is not a de Polignac number, because 509909 - 2⁸ = 509653 is a prime.

It is a Sophie Germain prime.

Together with 509911, it forms a pair of twin primes.

It is a Chen prime.

It is an Ulam number.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (509939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 254954 + 254955.

It is an arithmetic number, because the mean of its divisors is an integer number (254955).

2⁵⁰⁹⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

509909 is a deficient number, since it is larger than the sum of its proper divisors (1).

509909 is an equidigital number, since it uses as much as digits as its factorization.

509909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3645, while the sum is 32.

The square root of 509909 is about 714.0791272681. The cubic root of 509909 is about 79.8909451556.

The spelling of 509909 in words is "five hundred nine thousand, nine hundred nine".