199988309 has 2 divisors, whose sum is σ = 199988310. Its totient is φ = 199988308.

The previous prime is 199988303. The next prime is 199988311. The reversal of 199988309 is 903889991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 114425809 + 85562500 = 10697^2 + 9250^2 .

It is an emirp because it is prime and its reverse (903889991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 199988309 - 2²⁰ = 198939733 is a prime.

Together with 199988311, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199988303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99994154 + 99994155.

It is an arithmetic number, because the mean of its divisors is an integer number (99994155).

Almost surely, 2^199988309 is an apocalyptic number.

It is an amenable number.

199988309 is a deficient number, since it is larger than the sum of its proper divisors (1).

199988309 is an equidigital number, since it uses as much as digits as its factorization.

199988309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1259712, while the sum is 56.

The square root of 199988309 is about 14141.7222784214. The cubic root of 199988309 is about 584.7921525234.

The spelling of 199988309 in words is "one hundred ninety-nine million, nine hundred eighty-eight thousand, three hundred nine".