421 in words
421
four hundred twenty-one
421 is written four hundred twenty-one.
Ways to write it
- As an ordinal
- four hundred twenty-first
- Roman numeral
- CDXXI
- Expanded form
- 400 + 20 + 1
Place value
| Place | Digit | Value |
|---|---|---|
| hundreds | 4 | 400 |
| tens | 2 | 20 |
| ones | 1 | 1 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Prime
- Factors
- 1 and 421 (2 factors)
- First 10 multiples
- 421, 842, 1,263, 1,684, 2,105, 2,526, 2,947, 3,368, 3,789, 4,210
- Square
- 421 × 421 = 177,241
- Square root
- ≈ 20.52
- Sum of the digits
- 4 + 2 + 1 = 7
- Rounded to the nearest 10
- 420
- Rounded to the nearest 100
- 400
- Number before
- 420
- Number after
- 422
- In binary
110100101
Quick check
What number comes just after 421?
Show the answer
422
Is 421 even or odd?
Show the answer
Odd
What is 421 + 10?
Show the answer
431
Practice with a game
Factors, Multiples & Primes
Multiples, factors, prime numbers, square numbers and prime factors.
Roman Numerals
Read and write Roman numerals from I to 3,999.Frequently asked questions
How do you write 421 in words?
421 is written "four hundred twenty-one".
Is 421 a prime number?
Yes. 421 is a prime number: its only factors are 1 and 421.
What are the factors of 421?
The factors of 421 are 1 and 421.
How do you write 421 in Roman numerals?
421 in Roman numerals is CDXXI.