99 (ninety-nine) is the natural number following 98 and preceding 100.
In mathematics
99 is:
a composite number
a square-prime of the form (p2, q)
the 11th composite number of this form and the third of the form (32, q)
has an aliquot sum of 57, within an aliquot sequence of two composite numbers (99,57,23,1,0), to the Prime in the 23-aliquot tree.
a Kaprekar number
a lucky number
a palindromic number in base ten
the ninth repdigit
the sum of the cubes of three consecutive integers: 99 = 23 + 33 + 43.
the sum of the sums of the divisors of the first 11 positive integers.
99
70
=
1.4142
8571
…
{\displaystyle {\frac {99}{70}}=1.4142{\color {red}8571}\ldots }
is a commonly used approximation of the irrational number √2
".99" is frequently used as a price ender in pricing.