21,001 in words
21,001
twenty-one thousand one
21,001 is written twenty-one thousand one.
Ways to write it
- As an ordinal
- twenty-one thousand first
- Expanded form
- 20,000 + 1,000 + 1
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 1 | 1,000 |
| hundreds | 0 | 0 |
| tens | 0 | 0 |
| ones | 1 | 1 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Prime
- Factors
- 1 and 21,001 (2 factors)
- First 10 multiples
- 21,001, 42,002, 63,003, 84,004, 105,005, 126,006, 147,007, 168,008, 189,009, 210,010
- Square
- 21,001 × 21,001 = 441,042,001
- Square root
- ≈ 144.92
- Sum of the digits
- 2 + 1 + 0 + 0 + 1 = 4
- Rounded to the nearest 10
- 21,000
- Rounded to the nearest 100
- 21,000
- Rounded to the nearest 1000
- 21,000
- Number before
- 21,000
- Number after
- 21,002
- In binary
101001000001001
Quick check
What number comes just after 21,001?
Show the answer
21,002
Is 21,001 even or odd?
Show the answer
Odd
What is 21,001 + 10?
Show the answer
21,011
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 21,001 in words?
21,001 is written "twenty-one thousand one".
Is 21,001 a prime number?
Yes. 21,001 is a prime number: its only factors are 1 and 21,001.
What are the factors of 21,001?
The factors of 21,001 are 1 and 21,001.