199999809 has 12 divisors (see below), whose sum is σ = 289068052. Its totient is φ = 133250400.

The previous prime is 199999777. The next prime is 199999819. The reversal of 199999809 is 908999991.

199999809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 15800625 + 184199184 = 3975^2 + 13572^2 .

It is not a de Polignac number, because 199999809 - 2⁵ = 199999777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199999819) 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, 10779 + ... + 22719.

Almost surely, 2^199999809 is an apocalyptic number.

It is an amenable number.

199999809 is a deficient number, since it is larger than the sum of its proper divisors (89068243).

199999809 is a wasteful number, since it uses less digits than its factorization.

199999809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13808 (or 13805 counting only the distinct ones).

The product of its (nonzero) digits is 4251528, while the sum is 63.

The square root of 199999809 is about 14142.1288708596. The cubic root of 199999809 is about 584.8033614801.

The spelling of 199999809 in words is "one hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred nine".