21,720 in words
21,720
twenty-one thousand seven hundred and twenty
21,720 is written twenty-one thousand seven hundred and twenty.
Ways to write it
- As an ordinal
- twenty-one thousand seven hundred and twentieth
- Expanded form
- 20,000 + 1,000 + 700 + 20
Place value
| Place | Digit | Value |
|---|---|---|
| ten thousands | 2 | 20,000 |
| thousands | 1 | 1,000 |
| hundreds | 7 | 700 |
| tens | 2 | 20 |
| ones | 0 | 0 |
Number facts
- Even or odd
- Even
- Prime or composite
- Composite
- Factors
- 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120, 181, 362, 543, 724, 905, 1,086, 1,448, 1,810, 2,172, 2,715, 3,620, 4,344, 5,430, 7,240, 10,860 and 21,720 (32 factors)
- First 10 multiples
- 21,720, 43,440, 65,160, 86,880, 108,600, 130,320, 152,040, 173,760, 195,480, 217,200
- Square
- 21,720 × 21,720 = 471,758,400
- Square root
- ≈ 147.38
- Sum of the digits
- 2 + 1 + 7 + 2 + 0 = 12
- Rounded to the nearest 10
- 21,720
- Rounded to the nearest 100
- 21,700
- Rounded to the nearest 1000
- 22,000
- Number before
- 21,719
- Number after
- 21,721
- In binary
101010011011000
Quick check
What number comes just after 21,720?
Show the answer
21,721
Is 21,720 even or odd?
Show the answer
Even
What is 21,720 + 10?
Show the answer
21,730
Practise 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 21,720 in words?
21,720 is written "twenty-one thousand seven hundred and twenty".
Is 21,720 a prime number?
No. 21,720 is a composite number, because it has more than two factors.
What are the factors of 21,720?
The factors of 21,720 are 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120, 181, 362, 543, 724, 905, 1,086, 1,448, 1,810, 2,172, 2,715, 3,620, 4,344, 5,430, 7,240, 10,860 and 21,720.