A little back-of-the-envelope arithmetic

U.S. population as of 2021 is 289 million people (281 million, really, but who's counting).

The median age in the U.S. is 35.3.

That means 140 million people who meet the age requirement for being President.

Let's say half of those people are unqualified for some other reason. Any reason you like. Wrong color eyes. Wear ugly shoes. Anything.

That leaves 70 million people to choose from.

You can do the rest of this yourself.