This is the 13663rd most frequent German word.
einflussreichsten
"Most influential."
Here, 'einflussreichsten' is an adjective in its superlative form, describing the politicians who are most influential.
Er gehört zu den einflussreichsten Politikern des Landes.
He is among the most influential politicians in the country.
In this sentence, 'einflussreichsten' describes books, indicating they have the greatest impact on a generation.
Die einflussreichsten Bücher einer Generation prägen die Kultur nachhaltig.
The most influential books of a generation shape the culture profoundly.
Here, 'einflussreichsten' qualifies the events, pointing out those with the most significant influence in history.