What apps are best for scheduling appointments? ?

Question

I’m a recent college graduate and work in the hiring sector and I’m often overwhelmed with my call volume and meetings. I’ve been doing everything on a notebook (paper) and with cancellations and rescheduling, all the crossing out and whatnot is overwhelming me.

Does anyone who also has a busy work schedule and lots of appointments have any good recommendations on apps that help me manage my schedule In a more organized fashion?