20204209 has 2 divisors, whose sum is σ = 20204210. Its totient is φ = 20204208.

The previous prime is 20204207. The next prime is 20204221. The reversal of 20204209 is 90240202.

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., 15186609 + 5017600 = 3897^2 + 2240^2 .

It is a cyclic number.

It is not a de Polignac number, because 20204209 - 2¹ = 20204207 is a prime.

It is a super-2 number, since 2×20204209² = 816420122631362, which contains 22 as substring.

Together with 20204207, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20204203) 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, 10102104 + 10102105.

It is an arithmetic number, because the mean of its divisors is an integer number (10102105).

Almost surely, 2^20204209 is an apocalyptic number.

It is an amenable number.

20204209 is a deficient number, since it is larger than the sum of its proper divisors (1).

20204209 is an equidigital number, since it uses as much as digits as its factorization.

20204209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 20204209 is about 4494.9092315641. The cubic root of 20204209 is about 272.3624825871.

The spelling of 20204209 in words is "twenty million, two hundred four thousand, two hundred nine".