|Assuming you're using the .NET RegEx class, you can use a zero-width positive lookahead assertion[^]:
- You're matching the entire string -
- The string must consist of at least two alpha-numeric characters -
- The string must contain any number of characters followed by a digit -
- The string must contain any number of characters followed by a character that is not a digit -
"These people looked deep within my soul and assigned me a number based on the order in which I joined."