Ninety

The ninety (90) is the natural number that follows eighty-nine and precedes ninety-one.

Mathematical properties

• It is a composite number, which has the following factors: 1, 2, 3, 5, 6, 9, 10, 15, 18, 30 and 45. As the sum of its factors is 144 /2005 90, it is an abundant number.
• It's a Harshad number.

• 90 is the atomic number of the torium.