The number 21730
21730 is a composite number with 16 divisors. Its prime factorisation is 2 × 5 × 41 × 53. Divisors (16): 1, 2, 5, 10, 41, 53, 82, 106, 205, 265, 410, 530, 2173, 4346, 10865, 21730.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21730 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21730 is composite. Its prime factorisation is
- 3
The divisors add up to 40824; without 21730 itself that is 19094, so 21730 is deficient (19094 is less than 21730). Euler's totient φ(21730) = 8320 numbers up to 21730 share no factor with it.
- 4
The digits of 21730 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21730 = 2 \times 5 \times 41 \times 53 \]
21730 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 40824 |
| Euler totient φ(n) | 8320 |
| Square | 472192900 |
| Cube | 10260751717000 |
| Square root | 147.410990 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.173 × |
21730 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand seven hundred and thirty |
| Binary (base 2) | 101010011100010 |
| Octal (base 8) | 52342 |
| Hexadecimal (base 16) | 54E2 |
| Base 3 | 1002210211 |
| As time | 21730 seconds = 6 h 2 min 10 s |
Is 21730 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21730 ÷ 2 = 10865) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21730 ÷ 5 = 4346) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | A number is divisible by 7 if double the last digit and subtract it from the rest: the result is a multiple of 7. |
| 8 | No (remainder 2) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (21730 ÷ 10 = 2173) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 10) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21730 a prime number?
No. 21730 = 2 × 5 × 41 × 53, so it is divisible by 2.
What are the factors of 21730?
1, 2, 5, 10, 41, 53, 82, 106, 205, 265, 410, 530, 2173, 4346, 10865, 21730.
What is 21730 in binary?
101010011100010 (hexadecimal 54E2, octal 52342).
What is the square root of 21730?
About 147.4110.
Is 21730 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 21730?
It is a composite number with 16 divisors.