Really cool game!! Took me a bit to figure out but once I was able to understand how to I couldn't stop playing. THe music and sfx were integrated so well into the game.
One feedback is, When the number gets really big I would like to pull out the number I like. maybe a small popup to select the prime number would do the trick.
Anyhow you made a reallly cool game that I would play in my free time just chilling on my phone.
Kudos!!(My score was 130+. I think I did pretty good :D)