Paul Trevier Bateman & Harold G Diamond 
Analytic Number Theory: An Introductory Course [PDF ebook] 
An Introductory Course(Reprinted 2009)

This valuable book focuses on a collection of powerful methods of analysis that yield deep number-theoretical estimates. Particular attention is given to counting functions of prime numbers and multiplicative arithmetic functions. Both real variable (âelementaryâ) and complex variable (âanalyticâ) methods are employed. The reader is assumed to have knowledge of elementary number theory (abstract algebra will also do) and real and complex analysis. Specialized analytic techniques, including transform and Tauberian methods, are developed as needed.Comments and corrigenda for the book are found at www.math.uiuc.edu/~diamond/.