Simplify the following text for a Grade 6 native English-speaking person.
Original: This means there are 47 perfect numbers known , the largest being 243,112,609 ( 243,112,609 1 ) with 25,956,377 digits .
Simplified: The largest of these is 243,112,608 Ã -- ( 243,112,609 â ' 1 ) with 25,956,377 digits .