199990909 has 2 divisors, whose sum is σ = 199990910. Its totient is φ = 199990908.

The previous prime is 199990897. The next prime is 199990939. The reversal of 199990909 is 909099991.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 172396900 + 27594009 = 13130^2 + 5253^2 .

It is a cyclic number.

It is not a de Polignac number, because 199990909 - 2¹⁵ = 199958141 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 199990909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199990939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99995454 + 99995455.

It is an arithmetic number, because the mean of its divisors is an integer number (99995455).

Almost surely, 2^199990909 is an apocalyptic number.

It is an amenable number.

199990909 is a deficient number, since it is larger than the sum of its proper divisors (1).

199990909 is an equidigital number, since it uses as much as digits as its factorization.

199990909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 531441, while the sum is 55.

The square root of 199990909 is about 14141.8142046910. The cubic root of 199990909 is about 584.7946867599.

The spelling of 199990909 in words is "one hundred ninety-nine million, nine hundred ninety thousand, nine hundred nine".