On elliptic curves, modular forms, and the distribution of primes

In this thesis, we present four problems related to elliptic curves, modular forms, the distribution of primes, or some combination of the three. The first chapter surveys the relevant background material necessary for understanding the remainder of the thesis. The four following chapters present our problems of interest and their solutions. In the final chapter, we present our conclusions as well as a few possible directions for future research.;Hurwitz class numbers are known to have connections to many areas of number theory. In particular, they are intimately connected to the theory of binary quadratic forms, the structure of imaginary quadratic number fields, the theory of elliptic curves, and the theory of modular forms. Hurwitz class number identities of a certain type are studied in Chapter 2. To prove these identities, we demonstrate three different techniques. The first method involves a relation between the Hurwitz class number and elliptic curves, while the second and third methods involve connections to modular forms.;In Chapter 3, we explore the construction of finite field elements of high multiplicative order arising from modular curves. The field elements are constructed recursively using the equations that Elkies discovered to describe explicit modular towers. Using elementary techniques, we prove lower bounds for the orders of these elements.;Prime distribution has been a central theme in number theory for hundreds of years. Mean square error estimates for the Chebotarev Density Theorem are proved in Chapter 4. These estimates are related to the classical Barban-Davenport-Halberstam Theorem and will prove to be indispensable for our work in Chapter 5, where we take up the study of the Lang-Trotter Conjecture "on average" for elliptic curves defined over number fields. We begin Chapter 4 by proving upper bounds on the mean square error in Chebotarev's theorem. It is this upper bound which features as a key ingredient in Chapter 5. As another application of this upper bound, we continue in Chapter 4 to prove an asymptotic formula for the mean square error.;In Chapter 5, we turn to the discussion of the Lang-Trotter Conjecture for number fields "on average." The Lang-Trotter Conjecture is an important conjecture purporting to give information about the arithmetic of elliptic curves, the distribution of primes, and GL2 -representations of the absolute Galois group. In this chapter, we present some results in support of the conjecture. In particular, we show that the conjecture holds in an average sense when one averages over all elliptic curves defined over a given number field.