21 in Roman numerals is XXI. Split 21 into place values, write each part, and join them. The converter below works for any number from 1 to 3999.
What Is 21 in Roman Numerals?
Read XXI from left to right and add the values: XX (20) + I (1) = 21.
Roman numerals also number book chapters, outlines, and the names of kings and popes.
Convert Any Number to Roman Numerals
21: Thousands, Hundreds, Tens and Ones
| Place | Value | Roman |
|---|---|---|
| Tens | 20 | XX |
| Ones | 1 | I |
| Total | 21 | XXI |
Write the parts in order from largest to smallest to get XXI.
Roman Numeral Rules Behind XXI
| Symbol | I | V | X | L | C | D | M |
|---|---|---|---|---|---|---|---|
| Value | 1 | 5 | 10 | 50 | 100 | 500 | 1000 |
- Add symbols from largest to smallest: VI = 5 + 1.
- Repeat I, X, C or M up to three times: XXX = 30.
- Put a smaller symbol before a larger one to subtract: IV = 4, IX = 9.
XXI has no subtractive pair, so you only add the symbols from left to right.
Roman Numerals Close to 21
| Number | Roman numeral |
|---|---|
| 17 in Roman numerals | XVII |
| 18 in Roman numerals | XVIII |
| 19 in Roman numerals | XIX |
| 20 in Roman numerals | XX |
| 22 in Roman numerals | XXII |
| 23 in Roman numerals | XXIII |
| 24 in Roman numerals | XXIV |
| 25 in Roman numerals | XXV |
See the full list in the Roman numerals chart.
Quick Answers About XXI
What is 21 in Roman numerals?
21 in Roman numerals is XXI.
What is XXI as a number?
XXI equals 21.
How do you write 22 in Roman numerals?
22 in Roman numerals is XXII.
How many letters are in XXI?
XXI has 3 letters.
Quick Summary
21 is XXI. Split the number into thousands, hundreds, tens and ones, write each part, and join them in order.
