99 (ninety-nine) is the natural number following 98 and preceding 100.

99 is:

• a composite number; a square-prime, of the form (p², q). It is the 11th composite number of this form and the third of the form (3², q). It 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^[1]
• a lucky number
• a palindromic number
• 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.^[2]
• the highest two digit number in decimal.

• "99", a song by the band Toto on the Hydra album.
• "99 Bottles of Beer", a counting song.
• "99 Luftballons", a German-language song by the band Nena.
• "99 Problems", a song by Jay-Z on The Black Album.
• "99 Ways to Die", a song by Megadeth on the Hidden Treasures EP.

• In Abrahamic religions, 99 refers to the age at which Abram was renamed Abraham, as accounted by Genesis 17.
• In Christianity, 99 also refers to the number of sheep a shepherd central to the Parable of the Lost Sheep risks leaving unguarded to find one lost sheep.
• In Islam, 99 is the number of total names for Allah.

• The atomic number of einsteinium, an actinide.
• ".99" is frequently used as a price ender in pricing.
• 99, the jersey number of Wayne Gretzky, since permanently retired

Media related to 99 (number) at Wikimedia Commons