90 is a positive integer between 89 and 91.
90 is an even composite number.
It is also the number of primordial nuclides without energetically allowed baryon number-preserving decay modes.
In googology Edit
In Greek-based number-naming systems, 90 is associated with prefix "enneaconta-", and with prefix "nonaginti-" in Latin systems.
As a banknote denomination Edit
The third Burmese kyat had banknotes with this number in the denomination.