Every number doesn't have its own name. If you observe closely there is a pattern. From 21 to 99, you can observe that every digit at tens place decides the suffix and the digit at ones place decides the prefix.
In Hindi 40 and 41 use a different word for 40. 51 and 53 use a different word for 50. 55 and 45 use a different word for 5. Plus there are smaller but still significant differences between pretty much every number -- e.g. it's chauBees, but puchees and chauNtees.