What is the perfect resolution if want a clean non pixelated background

I use: 1700x1100 on my partner background and 1700x1131 for the normal background I had before.. if you check out my channel you'll see the quality I have :) I'm pretty sure it's not pixelated at all :)
72 shouldn't be pixelated :L If you made the image bigger or smaller by a certain amount, then yes it will be pixelated. If not then try 300 which is what I tend to use (photo/print quality)