21,121 in words
21,121
twenty-one thousand one hundred and twenty-one
21,121 is written twenty-one thousand one hundred and twenty-one.
Ways to write it
- As an ordinal
- twenty-one thousand one hundred and twenty-first
- Expanded form
- 20,000 + 1,000 + 100 + 20 + 1
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 1 | 1,000 |
| hundreds | 1 | 100 |
| tens | 2 | 20 |
| ones | 1 | 1 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Prime
- Factors
- 1 and 21,121 (2 factors)
- First 10 multiples
- 21,121, 42,242, 63,363, 84,484, 105,605, 126,726, 147,847, 168,968, 190,089, 211,210
- Square
- 21,121 × 21,121 = 446,096,641
- Square root
- ≈ 145.33
- Sum of the digits
- 2 + 1 + 1 + 2 + 1 = 7
- Rounded to the nearest 10
- 21,120
- Rounded to the nearest 100
- 21,100
- Rounded to the nearest 1000
- 21,000
- Number before
- 21,120
- Number after
- 21,122
- In binary
101001010000001
Quick check
What number comes just after 21,121?
Show the answer
21,122
Is 21,121 even or odd?
Show the answer
Odd
What is 21,121 + 10?
Show the answer
21,131
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 21,121 in words?
21,121 is written "twenty-one thousand one hundred and twenty-one".
Is 21,121 a prime number?
Yes. 21,121 is a prime number: its only factors are 1 and 21,121.
What are the factors of 21,121?
The factors of 21,121 are 1 and 21,121.