There is no correct answer for the number of countries in the world. I'd recommend this Map Men video on the difficulty of deciding what is or isn't a country: https://www.youtube.com/watch?v=3nB688xBYdY

There are some databases including territories and stuff that sometimes lands in the ~250 region, but should be stated if so. Closer to 200-210 or UNs "193 countries" tend to be a bit more common to use though, always depend on what exactly you see as a "country" I suppose.

There are 249 country codes, which is a possible definition used.