391 in words
391
three hundred and ninety-one
391 is written three hundred and ninety-one.
Ways to write it
- As an ordinal
- three hundred and ninety-first
- Roman numeral
- CCCXCI
- Expanded form
- 300 + 90 + 1
Place value
| Place | Digit | Value |
|---|---|---|
| hundreds | 3 | 300 |
| tens | 9 | 90 |
| ones | 1 | 1 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Composite
- Factors
- 1, 17, 23 and 391 (4 factors)
- First 10 multiples
- 391, 782, 1,173, 1,564, 1,955, 2,346, 2,737, 3,128, 3,519, 3,910
- Square
- 391 × 391 = 152,881
- Square root
- ≈ 19.77
- Sum of the digits
- 3 + 9 + 1 = 13
- Rounded to the nearest 10
- 390
- Rounded to the nearest 100
- 400
- Number before
- 390
- Number after
- 392
- In binary
110000111
Quick check
What number comes just after 391?
Show the answer
392
Is 391 even or odd?
Show the answer
Odd
What is 391 + 10?
Show the answer
401
Practise 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 391 in words?
391 is written "three hundred and ninety-one".
Is 391 a prime number?
No. 391 is a composite number, because it has more than two factors.
What are the factors of 391?
The factors of 391 are 1, 17, 23 and 391.
How do you write 391 in Roman numerals?
391 in Roman numerals is CCCXCI.