# 90

## 90 is an even composite number composed of three prime numbers multiplied together.

What does the number 90 look like?

This visualization shows the relationship between its 3 prime factors (large circles) and 12 divisors.

90 is an even composite number. It is composed of three distinct prime numbers multiplied together. It has a total of twelve divisors.

## Prime factorization of 90:

### 2 × 32 × 5

(2 × 3 × 3 × 5)

See below for interesting mathematical facts about the number 90 from the Numbermatics database.

### Names of 90

• Cardinal: 90 can be written as Ninety.

### Scientific notation

• Scientific notation: 9 × 101

### Factors of 90

• Number of distinct prime factors ω(n): 3
• Total number of prime factors Ω(n): 4
• Sum of prime factors: 10

### Divisors of 90

• Number of divisors d(n): 12
• Complete list of divisors:
• Sum of all divisors σ(n): 234
• Sum of proper divisors (its aliquot sum) s(n): 144
• 90 is an abundant number, because the sum of its proper divisors (144) is greater than itself. Its abundance is 54

### Bases of 90

• Binary: 10110102
• Base-36: 2I

### Squares and roots of 90

• 90 squared (902) is 8100
• 90 cubed (903) is 729000
• The square root of 90 is 9.4868329807
• The cube root of 90 is 4.4814047465

### Scales and comparisons

How big is 90?
• 90 seconds is equal to 1 minute, 30 seconds.
• To count from 1 to 90 would take you about forty-five seconds.

This is a very rough estimate, based on a speaking rate of half a second every third order of magnitude. If you speak quickly, you could probably say any randomly-chosen number between one and a thousand in around half a second. Very big numbers obviously take longer to say, so we add half a second for every extra x1000. (We do not count involuntary pauses, bathroom breaks or the necessity of sleep in our calculation!)

• A cube with a volume of 90 cubic inches would be around 0.4 feet tall.

### Recreational maths with 90

• 90 backwards is 09
• 90 is a Harshad number.
• The number of decimal digits it has is: 2
• The sum of 90's digits is 9
• More coming soon!