421 in Roman Numerals
421
C (subtracted)DXXI
four hundred twenty-one
How CDXXI is formed
| Place | Value | Symbols |
|---|---|---|
| Hundreds | 400 | C (subtracted)D |
| Tens | 20 | XX |
| Units | 1 | I |
| Total | 421 | CDXXI |
CDXXI is written one place at a time, from the largest to the smallest: CD (400) + XX (20) + I (1) = 421.
CD is the only subtraction: the C before the D takes away 100, so CD = 400.
Common mistakes
Wrong: CCCCXXI
Why isn't 421 written as CCCCXXI?
A symbol can't be repeated four times in a row. 400 is CD (500 − 100), not CCCC, so 421 is CDXXI.
Numbers near 421
Properties of 421
- Prime factors
- 421
- Divisors
- 1, 421
- Even or odd
- Odd
- Prime number
- Yes
- Letters in CDXXI
- 5
421 is a prime number: it can only be divided by 1 and by itself.
421,000 in Roman numerals
With a bar over it (vinculum), C̅D̅X̅X̅I̅ means 421 × 1,000 = 421,000. How Roman numerals work