199999609 has 2 divisors, whose sum is σ = 199999610. Its totient is φ = 199999608.

The previous prime is 199999607. The next prime is 199999649. The reversal of 199999609 is 906999991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 132710400 + 67289209 = 11520^2 + 8203^2 .

It is a cyclic number.

It is not a de Polignac number, because 199999609 - 2¹ = 199999607 is a prime.

Together with 199999607, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (199999601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99999804 + 99999805.

It is an arithmetic number, because the mean of its divisors is an integer number (99999805).

Almost surely, 2^199999609 is an apocalyptic number.

It is an amenable number.

199999609 is a deficient number, since it is larger than the sum of its proper divisors (1).

199999609 is an equidigital number, since it uses as much as digits as its factorization.

199999609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3188646, while the sum is 61.

The square root of 199999609 is about 14142.1217997866. The cubic root of 199999609 is about 584.8031665453.

The spelling of 199999609 in words is "one hundred ninety-nine million, nine hundred ninety-nine thousand, six hundred nine".