This is so cleeean! The gameplay feels super fun and smooth to use and the colour palette + aesthetics you've chosen fits the vibe really well. A great use of geometric shapes and patterns, also, and I loved the complexity of multitasking - trying to type in the numbers whilst still staying alive :P The enemies did feel a bit slow and high in health at some points, and so maybe some powerups or level obstacles could break up the monotony of continuously tapping to shoot. I see that you're looking at adding boss fights and a more interactive tutorial in a possible update, and I think they're both great ideas! The interactive tutorial especially would be great as the current one feels a bit wordy and most players, including myself, will skip it and only return when they can't figure out the game by playing it (also like myself :P)
Overall, a stunning entry! Great use of sound effects, and if you decide to go ahead with an update, best of luck! (better see some poppin', juicy particle effects, too!)