Task: Text Categorization
Input (English): At the age of 28, he solved the famous Basel problem, and he discovered the law of quadratic reciprocity. His contributions to number theory include the invention of the totient function, which gives the number of positive integers less than and coprime to a positive integer n. He developed analytic number theory, where he developed the theory of hyperbolic functions, and he is also considered the father of graph theory with the solving of the famous Knigsberg Bridge problem. FTP, name this most prolific mathematician in history, whose famous namesake formula connects complex numbers and trigonometry, and who was the namesake for the symbol of the natural log base.
Output (English): Science