Mathematicians

There were 4 mathematicians - Brahma, Shura, Prudencio and Nicholas - having lunch in a hotel. Suddenly, Brahma thought of 2 integer numbers greater than 1 and said, "The sum of the numbers is..." and he whispered the sum to Shura. Then he said, "The product of the numbers is..." and he whispered the product to Prudencio. After that, the following conversation took place:

Shura : Prudencio, I don't think that we know the numbers.

Prudencio : Aha! Now I know the numbers.

Shura : Oh, now I also know the numbers.

Nicholas : Now I also know the numbers.

What is the product of the numbers Brahma thought of?