<human>:  What is the name of the character who is a mathematician in the book ‘The Man Who Knew Infinity’?
<bot>: The character in the book The Man Who Knew Infinity is Ramanujan. Ramanujan was a famous Indian mathematician who lived in the early 1900s. He was the first person to prove that there are infinitely many prime numbers, and he made significant contributions to the fields of number theory and analytic number theory.