21,931 in words
21,931
twenty-one thousand nine hundred thirty-one
21,931 is written twenty-one thousand nine hundred thirty-one.
Ways to write it
- As an ordinal
- twenty-one thousand nine hundred thirty-first
- Expanded form
- 20,000 + 1,000 + 900 + 30 + 1
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 1 | 1,000 |
| hundreds | 9 | 900 |
| tens | 3 | 30 |
| ones | 1 | 1 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Composite
- Factors
- 1, 7, 13, 91, 241, 1,687, 3,133 and 21,931 (8 factors)
- First 10 multiples
- 21,931, 43,862, 65,793, 87,724, 109,655, 131,586, 153,517, 175,448, 197,379, 219,310
- Square
- 21,931 × 21,931 = 480,968,761
- Square root
- ≈ 148.09
- Sum of the digits
- 2 + 1 + 9 + 3 + 1 = 16
- Rounded to the nearest 10
- 21,930
- Rounded to the nearest 100
- 21,900
- Rounded to the nearest 1000
- 22,000
- Number before
- 21,930
- Number after
- 21,932
- In binary
101010110101011
Quick check
What number comes just after 21,931?
Show the answer
21,932
Is 21,931 even or odd?
Show the answer
Odd
What is 21,931 + 10?
Show the answer
21,941
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 21,931 in words?
21,931 is written "twenty-one thousand nine hundred thirty-one".
Is 21,931 a prime number?
No. 21,931 is a composite number, because it has more than two factors.
What are the factors of 21,931?
The factors of 21,931 are 1, 7, 13, 91, 241, 1,687, 3,133 and 21,931.