ABSTRACT. Let θ and ψ be the Chebyshev functions. We denote ψ2 (x) = ψ(x) − θ(x) and
ρ(x) = ψ(x)/θ(x). We study subadditive and Landau-type properties for θ, ψ, and ψ2 . We show
that ρ is subadditive and submultiplicative. Finally, we consider the prime counting function
π(x) and show that π(x)π(y) < π(xy) for all x, y ≥ √53.