91 (ninety-one) is a positive integer following 90 and preceding 92. Its ordinal form is written "ninety-first" or 91st.

Properties Edit

91 is an odd composite number.

91 is the 13th triangular number, and therefore the number of tiles in a double-12 domino set.

In googology Edit

In Greek-based number-naming systems, 91 is associated with prefix "henenneaconta-", and with prefix "unnonaginti-" in Latin systems.