A version of the prime number theorem states that the number \(\pi(x)\) of prime numbers \(p \le x\) is asymptotically equal to Li\((x) = \int_0^x \frac{dt}{\log t}\). J. E. Littlewood [C. R. Acad. Sci., Paris 158, 1869–1872 (1914; JFM 45.0305.01)] proved that \(\pi(x) - \mathrm{Li}(x)\) changes sign infinitely often. For small values of \(x\), we have \(\pi(x) < \mathrm{Li}(x)\), and one may ask for the smallest value of \(x\) such that \(\pi(x) > \mathrm{Li}(x)\). It is difficult to come up with more boring questions in number theory – BUT: the mathematics needed for understanding this question and for getting closer to an answer is very beautiful, and the author does an outstanding job in explaining the necessary background: Riemann’s zeta function, its Euler product expansion, the functional equation, Riemann’s formula, Zagier’s exposition of Newman’s proof of the prime number formula (see [D. Zagier, Am. Math. Mon. 104, No. 8, 705–708 (1997; Zbl 0887.11039)]), and finally Littlewood’s theorem. The book is accessible to anyone with a solid background in complex analysis and is highly recommended.