2 is the lowest Mersenne prime.

Did you mean what Mersenne numbers are prime? If a number is a prime, how is it not a prime at the same time? Anyways, M11, or (2^11) - 1, I think is the lowest Mersenne Number Mp that isn't prime, when p is prime. Any Mersenne Number where p is not prime cannot be prime.

Mersenne prime is a kind of number - a prime. Being a number, it was not capable of discovering anything

Let p = any prime number.

(2p -1) is called a Mersenne number. Any such number that is prime is called a Mersenne Prime. Father Mersenne wrote a list of numbers of this type which he thought were prime, but a few were not.

In fact, most of the large Mersenne numbers are not prime, but all the really large numbers that have been proved to be prime are Mersenne Primes.