21,831 in words
21,831
twenty-one thousand eight hundred thirty-one
21,831 is written twenty-one thousand eight hundred thirty-one.
Ways to write it
- As an ordinal
- twenty-one thousand eight hundred thirty-first
- Expanded form
- 20,000 + 1,000 + 800 + 30 + 1
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 1 | 1,000 |
| hundreds | 8 | 800 |
| tens | 3 | 30 |
| ones | 1 | 1 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Composite
- Factors
- 1, 3, 19, 57, 383, 1,149, 7,277 and 21,831 (8 factors)
- First 10 multiples
- 21,831, 43,662, 65,493, 87,324, 109,155, 130,986, 152,817, 174,648, 196,479, 218,310
- Square
- 21,831 × 21,831 = 476,592,561
- Square root
- ≈ 147.75
- Sum of the digits
- 2 + 1 + 8 + 3 + 1 = 15
- Rounded to the nearest 10
- 21,830
- Rounded to the nearest 100
- 21,800
- Rounded to the nearest 1000
- 22,000
- Number before
- 21,830
- Number after
- 21,832
- In binary
101010101000111
Quick check
What number comes just after 21,831?
Show the answer
21,832
Is 21,831 even or odd?
Show the answer
Odd
What is 21,831 + 10?
Show the answer
21,841
Practice with a game
Factors, Multiples & Primes
Multiples, factors, prime numbers, square numbers and prime factors.
Number Patterns
Find the missing number in a sequence.Frequently asked questions
How do you write 21,831 in words?
21,831 is written "twenty-one thousand eight hundred thirty-one".
Is 21,831 a prime number?
No. 21,831 is a composite number, because it has more than two factors.
What are the factors of 21,831?
The factors of 21,831 are 1, 3, 19, 57, 383, 1,149, 7,277 and 21,831.