21,021 in words
21,021
twenty-one thousand and twenty-one
21,021 is written twenty-one thousand and twenty-one.
Ways to write it
- As an ordinal
- twenty-one thousand and twenty-first
- Expanded form
- 20,000 + 1,000 + 20 + 1
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 1 | 1,000 |
| hundreds | 0 | 0 |
| tens | 2 | 20 |
| ones | 1 | 1 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Composite
- Factors
- 1, 3, 7, 11, 13, 21, 33, 39, 49, 77, 91, 143, 147, 231, 273, 429, 539, 637, 1,001, 1,617, 1,911, 3,003, 7,007 and 21,021 (24 factors)
- First 10 multiples
- 21,021, 42,042, 63,063, 84,084, 105,105, 126,126, 147,147, 168,168, 189,189, 210,210
- Square
- 21,021 × 21,021 = 441,882,441
- Square root
- ≈ 144.99
- Sum of the digits
- 2 + 1 + 0 + 2 + 1 = 6
- Rounded to the nearest 10
- 21,020
- Rounded to the nearest 100
- 21,000
- Rounded to the nearest 1000
- 21,000
- Number before
- 21,020
- Number after
- 21,022
- In binary
101001000011101
Quick check
What number comes just after 21,021?
Show the answer
21,022
Is 21,021 even or odd?
Show the answer
Odd
What is 21,021 + 10?
Show the answer
21,031
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 21,021 in words?
21,021 is written "twenty-one thousand and twenty-one".
Is 21,021 a prime number?
No. 21,021 is a composite number, because it has more than two factors.
What are the factors of 21,021?
The factors of 21,021 are 1, 3, 7, 11, 13, 21, 33, 39, 49, 77, 91, 143, 147, 231, 273, 429, 539, 637, 1,001, 1,617, 1,911, 3,003, 7,007 and 21,021.