The number 55721
55721 is the 5656th prime number. Its only divisors are 1 and 55721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 55721: the 5656th prime number.
- 2
55721 is prime, so its only factors are 1 and 55721. It is the 5656th prime; the next prime is 55733 and the one before is 55717.
- 3
The divisors add up to 55722; without 55721 itself that is 1, so 55721 is deficient (1 is less than 55721). Euler's totient φ(55721) = 55720 numbers up to 55721 share no factor with it.
- 4
The digits of 55721 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 259 steps to reach 1.
55721 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 55722 |
| Euler totient φ(n) | 55720 |
| Square | 3104829841 |
| Cube | 173004223570361 |
| Square root | 236.052960 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 259 |
| Scientific notation | 5.5721 × |
55721 in other forms
| Form | Value |
|---|---|
| In words | fifty-five thousand seven hundred and twenty-one |
| Binary (base 2) | 1101100110101001 |
| Octal (base 8) | 154651 |
| Hexadecimal (base 16) | D9A9 |
| Base 3 | 2211102202 |
| As time | 55721 seconds = 15 h 28 min 41 s |
Is 55721 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 2) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 55721 a prime number?
Yes. 55721 is divisible only by 1 and itself.
What are the factors of 55721?
1, 55721.
What is 55721 in binary?
1101100110101001 (hexadecimal D9A9, octal 154651).
What is the square root of 55721?
About 236.0530.
Is 55721 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 55721?
55721 is the 5656th prime number.