821 in Roman Numerals
821
DCCCXXI
eight hundred twenty-one
How DCCCXXI is formed
| Place | Value | Symbols |
|---|---|---|
| Hundreds | 800 | DCCC |
| Tens | 20 | XX |
| Units | 1 | I |
| Total | 821 | DCCCXXI |
DCCCXXI is written one place at a time, from the largest to the smallest: DCCC (800) + XX (20) + I (1) = 821.
Common mistakes
Wrong: CCMXXI
Why isn't 821 written as CCMXXI?
Only one smaller symbol can stand before a larger one, so CCM doesn't work. 800 is DCCC (500 + 300), so 821 is DCCCXXI.
Numbers near 821
Properties of 821
- Prime factors
- 821
- Divisors
- 1, 821
- Even or odd
- Odd
- Prime number
- Yes
- Letters in DCCCXXI
- 7
821 is a prime number: it can only be divided by 1 and by itself.
821,000 in Roman numerals
With a bar over it (vinculum), D̅C̅C̅C̅X̅X̅I̅ means 821 × 1,000 = 821,000. How Roman numerals work