199997909 has 4 divisors (see below), whose sum is σ = 201767916. Its totient is φ = 198227904.

The previous prime is 199997899. The next prime is 199997927. The reversal of 199997909 is 909799991.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 51523684 + 148474225 = 7178^2 + 12185^2 .

It is a cyclic number.

It is not a de Polignac number, because 199997909 - 2⁴ = 199997893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199997989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 884834 + ... + 885059.

It is an arithmetic number, because the mean of its divisors is an integer number (50441979).

Almost surely, 2^199997909 is an apocalyptic number.

It is an amenable number.

199997909 is a deficient number, since it is larger than the sum of its proper divisors (1770007).

199997909 is a wasteful number, since it uses less digits than its factorization.

199997909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1770006.

The product of its (nonzero) digits is 3720087, while the sum is 62.

The square root of 199997909 is about 14142.0616955237. The cubic root of 199997909 is about 584.8015095951.

The spelling of 199997909 in words is "one hundred ninety-nine million, nine hundred ninety-seven thousand, nine hundred nine".