The German polyglot Emil Krebs allegedly mastered 68 languages. Which, frankly, I find unbelievable. Unfortunately, I cannot find any reliable and convincing source.
Is there solid evidence that Emil Krebs mastered 68 languages?
The actual number of languages is rather unimportant, it is the order of magnitude that strikes me.
(EDIT: Upon request, I have removed all my research from the question. You might want to have a look at the edit history.)