21,820 in words
21,820
twenty-one thousand eight hundred twenty
21,820 is written twenty-one thousand eight hundred twenty.
Ways to write it
- As an ordinal
- twenty-one thousand eight hundred twentieth
- Expanded form
- 20,000 + 1,000 + 800 + 20
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 1 | 1,000 |
| hundreds | 8 | 800 |
| tens | 2 | 20 |
| ones | 0 | 0 |
Number facts
- Even or odd
- Even
- Prime or composite
- Composite
- Factors
- 1, 2, 4, 5, 10, 20, 1,091, 2,182, 4,364, 5,455, 10,910 and 21,820 (12 factors)
- First 10 multiples
- 21,820, 43,640, 65,460, 87,280, 109,100, 130,920, 152,740, 174,560, 196,380, 218,200
- Square
- 21,820 × 21,820 = 476,112,400
- Square root
- ≈ 147.72
- Sum of the digits
- 2 + 1 + 8 + 2 + 0 = 13
- Rounded to the nearest 10
- 21,820
- Rounded to the nearest 100
- 21,800
- Rounded to the nearest 1000
- 22,000
- Number before
- 21,819
- Number after
- 21,821
- In binary
101010100111100
Quick check
What number comes just after 21,820?
Show the answer
21,821
Is 21,820 even or odd?
Show the answer
Even
What is 21,820 + 10?
Show the answer
21,830
Practise with a game
Factors, Multiples & Primes
Multiples, factors, prime numbers, square numbers and prime factors.
Number Patterns
Find the missing number in a sequence.Frequently asked questions
How do you write 21,820 in words?
21,820 is written "twenty-one thousand eight hundred twenty".
Is 21,820 a prime number?
No. 21,820 is a composite number, because it has more than two factors.
What are the factors of 21,820?
The factors of 21,820 are 1, 2, 4, 5, 10, 20, 1,091, 2,182, 4,364, 5,455, 10,910 and 21,820.