21,009 in words
21,009
twenty-one thousand nine
21,009 is written twenty-one thousand nine.
Ways to write it
- As an ordinal
- twenty-one thousand ninth
- Expanded form
- 20,000 + 1,000 + 9
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 1 | 1,000 |
| hundreds | 0 | 0 |
| tens | 0 | 0 |
| ones | 9 | 9 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Composite
- Factors
- 1, 3, 47, 141, 149, 447, 7,003 and 21,009 (8 factors)
- First 10 multiples
- 21,009, 42,018, 63,027, 84,036, 105,045, 126,054, 147,063, 168,072, 189,081, 210,090
- Square
- 21,009 × 21,009 = 441,378,081
- Square root
- ≈ 144.94
- Sum of the digits
- 2 + 1 + 0 + 0 + 9 = 12
- Rounded to the nearest 10
- 21,010
- Rounded to the nearest 100
- 21,000
- Rounded to the nearest 1000
- 21,000
- Number before
- 21,008
- Number after
- 21,010
- In binary
101001000010001
Quick check
What number comes just after 21,009?
Show the answer
21,010
Is 21,009 even or odd?
Show the answer
Odd
What is 21,009 + 10?
Show the answer
21,019
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 21,009 in words?
21,009 is written "twenty-one thousand nine".
Is 21,009 a prime number?
No. 21,009 is a composite number, because it has more than two factors.
What are the factors of 21,009?
The factors of 21,009 are 1, 3, 47, 141, 149, 447, 7,003 and 21,009.