The number 21767
21767 is the 2442nd prime number. Its only divisors are 1 and 21767.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21767: the 2442nd prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21767 is prime, so its only factors are 1 and 21767. It is the 2442nd prime; the next prime is 21773 and the one before is 21757.
- 3
The divisors add up to 21768; without 21767 itself that is 1, so 21767 is deficient (1 is less than 21767). Euler's totient φ(21767) = 21766 numbers up to 21767 share no factor with it.
- 4
The digits of 21767 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 180 steps to reach 1.
21767 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21768 |
| Euler totient φ(n) | 21766 |
| Square | 473802289 |
| Cube | 10313254424663 |
| Square root | 147.536436 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 180 |
| Scientific notation | 2.1767 × |
21767 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand seven hundred and sixty-seven |
| Binary (base 2) | 101010100000111 |
| Octal (base 8) | 52407 |
| Hexadecimal (base 16) | 5507 |
| Base 3 | 1002212012 |
| As time | 21767 seconds = 6 h 2 min 47 s |
Is 21767 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 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | 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 4) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 7) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21767 a prime number?
Yes. 21767 is divisible only by 1 and itself.
What are the factors of 21767?
1, 21767.
What is 21767 in binary?
101010100000111 (hexadecimal 5507, octal 52407).
What is the square root of 21767?
About 147.5364.
Is 21767 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 21767?
21767 is the 2442nd prime number; a happy number: repeatedly adding the squares of its digits reaches 1.