# 21780

## 21,780 is an even composite number composed of four prime numbers multiplied together.

What does the number 21780 look like?

This visualization shows the relationship between its 4 prime factors (large circles) and 54 divisors.

21780 is an even composite number. It is composed of four distinct prime numbers multiplied together. It has a total of fifty-four divisors.

## Prime factorization of 21780:

### 22 × 32 × 5 × 112

(2 × 2 × 3 × 3 × 5 × 11 × 11)

See below for interesting mathematical facts about the number 21780 from the Numbermatics database.

### Names of 21780

• Cardinal: 21780 can be written as Twenty-one thousand, seven hundred eighty.

### Scientific notation

• Scientific notation: 2.178 × 104

### Factors of 21780

• Number of distinct prime factors ω(n): 4
• Total number of prime factors Ω(n): 7
• Sum of prime factors: 21

### Divisors of 21780

• Number of divisors d(n): 54
• Complete list of divisors:
• Sum of all divisors σ(n): 72618
• Sum of proper divisors (its aliquot sum) s(n): 50838
• 21780 is an abundant number, because the sum of its proper divisors (50838) is greater than itself. Its abundance is 29058

### Bases of 21780

• Binary: 1010101000101002
• Base-36: GT0

### Squares and roots of 21780

• 21780 squared (217802) is 474368400
• 21780 cubed (217803) is 10331743752000
• The square root of 21780 is 147.5804865149
• The cube root of 21780 is 27.9266789165

### Scales and comparisons

How big is 21780?
• 21,780 seconds is equal to 6 hours, 3 minutes.
• To count from 1 to 21,780 would take you about six hours.

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 21780 cubic inches would be around 2.3 feet tall.

### Recreational maths with 21780

• 21780 backwards is 08712
• 21780 is a Harshad number.
• The number of decimal digits it has is: 5
• The sum of 21780's digits is 18
• More coming soon!