9

9 (nine) is a positive integer following 8 and preceding 10. Its ordinal form is written "9th" or "ninth".
== Properties ==
9 is the smallest number that is both and . It is the 3rd .
*9 is also equal to !4 using subfactorial.
*Its prime factorization is 9 = 3².
*9 is one of two known odd unitary superperfect numbers. The other one is 165.
*A 9 sided polygon is called an enneagon or a nonagon.
== In googology ==
*Some googologisms based on 9 are googolnoniplex and superenn.
*9 can be named "garthree" with the gar- prefix.
*In Greek-based number naming systems, 9 is associated with prefix ennea-, and with prefix nona- or novem- in Latin systems
*Username5243 coined the name Ternary-Goodol for this number, and it's equal to 3[1]2 in Username5243's Array Notation.Part 1 - My Large Numbers
*Binary198 calls this number hyper, and it's equal to \([2,\omega^2]\) using Ordinal Array Notation.
=== Googological functions returning 9 ===
*Gijswijt's sequence: \(c(3)=9\)
*Laver table: \(q(4)=9\)
*Mixed factorial: \(3^*=9\)
*Expostfacto function: \(\mathrm{expostfacto}(3)=9\)
*Exponential factorial: \(3!1=9\)
== Sources ==
es:9
Category:Numbers
Category:Class 1
Category:Numbers 0-99
Category:Numbers with 1 to 2 digits
Category:Powers of 3
Category:Gar-
Category:Googol Regiment