Based on a series of lectures at Haverford College, Hans Rademacher presents an accessible introduction to number theory. Requiring no prior knowledge of the subject, the text covers foundational theorems like prime factorization and quadratic reciprocity, detailed cyclotomy, and Gaussian sums. It addresses analytic number theory through asymptotic laws, Dirichlet’s theorem on primes in an arithmetical progression, and V. Brun’s twin prime theorem. Rademacher’s unique approach integrates analytical methods with arithmetic results, offering both exact identities and asymptotic insights. Lectures on Elementary Number Theory is a classic work that remains influential, bridging foundational theory with modern analytical advances.