205137209 has 2 divisors, whose sum is σ = 205137210. Its totient is φ = 205137208.

The previous prime is 205137193. The next prime is 205137259. The reversal of 205137209 is 902731502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 152893225 + 52243984 = 12365^2 + 7228^2 .

It is a cyclic number.

It is not a de Polignac number, because 205137209 - 2⁴ = 205137193 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (205137259) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102568604 + 102568605.

It is an arithmetic number, because the mean of its divisors is an integer number (102568605).

Almost surely, 2^205137209 is an apocalyptic number.

It is an amenable number.

205137209 is a deficient number, since it is larger than the sum of its proper divisors (1).

205137209 is an equidigital number, since it uses as much as digits as its factorization.

205137209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 205137209 is about 14322.6118079071. The cubic root of 205137209 is about 589.7683750375.

The spelling of 205137209 in words is "two hundred five million, one hundred thirty-seven thousand, two hundred nine".