208309 has 2 divisors, whose sum is σ = 208310. Its totient is φ = 208308.

The previous prime is 208291. The next prime is 208319. The reversal of 208309 is 903802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 184900 + 23409 = 430^2 + 153^2 .

It is a cyclic number.

It is not a de Polignac number, because 208309 - 2⁵ = 208277 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 208309.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (208319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104154 + 104155.

It is an arithmetic number, because the mean of its divisors is an integer number (104155).

2²⁰⁸³⁰⁹ is an apocalyptic number.

It is an amenable number.

208309 is a deficient number, since it is larger than the sum of its proper divisors (1).

208309 is an equidigital number, since it uses as much as digits as its factorization.

208309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 208309 is about 456.4088079781. The cubic root of 208309 is about 59.2792469564.

Adding to 208309 its reverse (903802), we get a palindrome (1112111).

The spelling of 208309 in words is "two hundred eight thousand, three hundred nine".