A prime number is a number with only two factors, itself and one (29 for example). Find the largest prime number that remains a prime number when the right most digit is removed until only one digit remains (73 fits this pattern as both 73 and 7 are prime numbers, for example).

– This puzzle was suggested by Paul Cleary

Remember, to solve this puzzle and appear on the leaderboard, email both your solution and your source code (in any language) to lewiscornwall13@gmail.com. Good luck!!