810809909 has 12 divisors (see below), whose sum is σ = 1015740684. Its totient is φ = 641519424.

The previous prime is 810809903. The next prime is 810809957. The reversal of 810809909 is 909908018.

It can be written as a sum of positive squares in 2 ways, for example, as 76562500 + 734247409 = 8750^2 + 27097^2 .

It is not a de Polignac number, because 810809909 - 2²⁴ = 794032693 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 810809909.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (810809903) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 635792 + ... + 637065.

It is an arithmetic number, because the mean of its divisors is an integer number (84645057).

Almost surely, 2^810809909 is an apocalyptic number.

It is an amenable number.

810809909 is a deficient number, since it is larger than the sum of its proper divisors (204930775).

810809909 is a wasteful number, since it uses less digits than its factorization.

810809909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1272884 (or 1272877 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 44.

The square root of 810809909 is about 28474.7240372931. The cubic root of 810809909 is about 932.4803366347.

The spelling of 810809909 in words is "eight hundred ten million, eight hundred nine thousand, nine hundred nine".