Are All Perfect Numbers Even?

Open Question
It is known that an even number is perfect iff it is of the form $$2^{n-1} \left({2^n - 1}\right)$$, where $$2^n - 1$$ is prime.

It is not known whether there exist any odd perfect numbers. None have ever been found.

However, it is known that no odd perfect number contains less than 100 digits.