We study expressions of the type
, where
is a nonnegative real number,
is an arithmetic function satisfying some conditions, and the product
is over the primes
. We begin by proving that such expressions can be
expressed by using the
function, without reference to
prime numbers; we illustrate this result with several examples. The rest
of the paper is devoted to studying two particular cases related
to
and
. In both cases, we find arithmetic
properties and analytic estimates for the underlying expressions.