How can I make paint less sticky?

I spray painted a hollowed-out book from Pier 1 Imports using Rust-Oleum 2x Ultra Cover Satin Paint and Primer about a week ago, maybe two, but one side is still a too tacky deal with, but not enough to mess up the coat. One side was the same way for awhile, but it solved itself after I left it sit face-down for a day or two, but that didn't work on the other side. What can I do to dry the paint?

Solvent based paint will benefit from a lot of air, so placing the book in a fan forced enclosure can speed things up.
Oil based paint is a different story as the oil needs to oxidize to harden, slightly elevated temps and a lot of fresh air can help.
However, if the object is very absorbent and no sealer was used prior to painting it can take weeks for paint to fully cure and harden.

so using a hair dryer would probably be a good first try

The "best" try would be to use the right amount of thinner and to apply the coats thin enough so they can dry before the next layer comes.
Putting a 2mm layer of paint onto something might cause the paint to take some time to dry ;)
And when it comes to oil based paints it is almost like alchemy with the things people add to "cure" the paint faster.
Just check the difference if linseed oil is used as the base.
Plain takes forever to fully dry, use boiled linseed oil and it goes down to under 2 weeks.

Bake under a sunlamp.

A heater that blows hot air on it will work.

The main point do it where it will get lots of fresh air and don't let it get too hot.