# 21821

## 21,821 is a prime number. Like all primes greater than two, it is odd and has no factors apart from itself and one.

What does the number 21821 look like?

As a prime, it is not composed of any other numbers and has no internal structure.

21821 is a prime number. Like all primes (except two), it is an odd number.

## Prime factorization of 21821:

### 21821

See below for interesting mathematical facts about the number 21821 from the Numbermatics database.

### Names of 21821

• Cardinal: 21821 can be written as Twenty-one thousand, eight hundred twenty-one.

### Scientific notation

• Scientific notation: 2.1821 × 104

### Factors of 21821

• Number of distinct prime factors ω(n): 1
• Total number of prime factors Ω(n): 1
• Sum of prime factors: 21821

### Divisors of 21821

• Number of divisors d(n): 2
• Complete list of divisors:
• Sum of all divisors σ(n): 21822
• Sum of proper divisors (its aliquot sum) s(n): 1
• 21821 is a deficient number, because the sum of its proper divisors (1) is less than itself. Its deficiency is 21820

### Bases of 21821

• Binary: 1010101001111012
• Base-36: GU5

### Squares and roots of 21821

• 21821 squared (218212) is 476156041
• 21821 cubed (218213) is 10390200970661
• The square root of 21821 is 147.7193284577
• The cube root of 21821 is 27.9441915599

### Scales and comparisons

How big is 21821?
• 21,821 seconds is equal to 6 hours, 3 minutes, 41 seconds.
• To count from 1 to 21,821 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 21821 cubic inches would be around 2.3 feet tall.

### Recreational maths with 21821

• 21821 backwards is 12812
• The number of decimal digits it has is: 5
• The sum of 21821's digits is 14
• More coming soon!

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Numbermatics. (2023). Number 21821 - Facts about the integer. Retrieved 9 December 2023, from https://numbermatics.com/n/21821/

Chicago style:
Numbermatics. 2023. "Number 21821 - Facts about the integer". https://numbermatics.com/n/21821/

The information we have on file for 21821 includes mathematical data and numerical statistics calculated using standard algorithms and methods. We are adding more all the time. If there are any features you would like to see, please contact us. Information provided for educational use, intellectual curiosity and fun!

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