21,521 in words
21,521
twenty-one thousand five hundred and twenty-one
21,521 is written twenty-one thousand five hundred and twenty-one.
Ways to write it
- As an ordinal
- twenty-one thousand five hundred and twenty-first
- Expanded form
- 20,000 + 1,000 + 500 + 20 + 1
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 1 | 1,000 |
| hundreds | 5 | 500 |
| tens | 2 | 20 |
| ones | 1 | 1 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Prime
- Factors
- 1 and 21,521 (2 factors)
- First 10 multiples
- 21,521, 43,042, 64,563, 86,084, 107,605, 129,126, 150,647, 172,168, 193,689, 215,210
- Square
- 21,521 × 21,521 = 463,153,441
- Square root
- ≈ 146.70
- Sum of the digits
- 2 + 1 + 5 + 2 + 1 = 11
- Rounded to the nearest 10
- 21,520
- Rounded to the nearest 100
- 21,500
- Rounded to the nearest 1000
- 22,000
- Number before
- 21,520
- Number after
- 21,522
- In binary
101010000010001
Quick check
What number comes just after 21,521?
Show the answer
21,522
Is 21,521 even or odd?
Show the answer
Odd
What is 21,521 + 10?
Show the answer
21,531
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 21,521 in words?
21,521 is written "twenty-one thousand five hundred and twenty-one".
Is 21,521 a prime number?
Yes. 21,521 is a prime number: its only factors are 1 and 21,521.
What are the factors of 21,521?
The factors of 21,521 are 1 and 21,521.