21,921 in words
21,921
twenty-one thousand nine hundred and twenty-one
21,921 is written twenty-one thousand nine hundred and twenty-one.
Ways to write it
- As an ordinal
- twenty-one thousand nine hundred and twenty-first
- Expanded form
- 20,000 + 1,000 + 900 + 20 + 1
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 1 | 1,000 |
| hundreds | 9 | 900 |
| tens | 2 | 20 |
| ones | 1 | 1 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Composite
- Factors
- 1, 3, 7,307 and 21,921 (4 factors)
- First 10 multiples
- 21,921, 43,842, 65,763, 87,684, 109,605, 131,526, 153,447, 175,368, 197,289, 219,210
- Square
- 21,921 × 21,921 = 480,530,241
- Square root
- ≈ 148.06
- Sum of the digits
- 2 + 1 + 9 + 2 + 1 = 15
- Rounded to the nearest 10
- 21,920
- Rounded to the nearest 100
- 21,900
- Rounded to the nearest 1000
- 22,000
- Number before
- 21,920
- Number after
- 21,922
- In binary
101010110100001
Quick check
What number comes just after 21,921?
Show the answer
21,922
Is 21,921 even or odd?
Show the answer
Odd
What is 21,921 + 10?
Show the answer
21,931
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 21,921 in words?
21,921 is written "twenty-one thousand nine hundred and twenty-one".
Is 21,921 a prime number?
No. 21,921 is a composite number, because it has more than two factors.
What are the factors of 21,921?
The factors of 21,921 are 1, 3, 7,307 and 21,921.