His wikipedia page goes into more detail on that front. Considered the top mathematician of his time (with also major contributions to physics and computer sci

His wikipedia page goes into more detail on that front. Considered the top mathematician of his time (with also major contributions to physics and computer science), other world-class mathematicians and physicists being in awe of his abilities, sometimes solving (never before answered) math problems easily, being able to recite word-for-word the books and articles he read, years after reading them, simultaneously translating them as necessary, etc. Ordinarily that would be hyperbole...