In this monograph, we study a class of representations of arithmetic functions, and corresponding operator-theoretic and free-probabilistic properties. We associate given arithmetic functions to certain matrices, and study free-probabilistic structures on such matrices determined by prime-powers. By understanding such matrices as operators acting on an "indefinite" inner product space, we derive operator-theoretic properties of them. This study is one of the frontier works, providing connections between modern number theory, and operator theory, via free probability with help of...