The English language doesn’t allow numbers in the middle of written words, but the English character set is a little bit larger than 26 characters. It has 26 capital letters, 26 lowercase letters, 10 digits (0-9) and a handful of other common characters like a dash (hyphen) and an underscore. In short, there are ~36 characters that are considered “punctuation” but it’s easier to remember that the English language has 26 alphanumeric characters only.