The number 21143
21143 is the 2376th prime number. Its only divisors are 1 and 21143.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21143: the 2376th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21143 is prime, so its only factors are 1 and 21143. It is the 2376th prime; the next prime is 21149 and the one before is 21139.
- 3
The divisors add up to 21144; without 21143 itself that is 1, so 21143 is deficient (1 is less than 21143). Euler's totient φ(21143) = 21142 numbers up to 21143 share no factor with it.
- 4
The digits of 21143 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 105 steps to reach 1.
21143 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21144 |
| Euler totient φ(n) | 21142 |
| Square | 447026449 |
| Cube | 9451480211207 |
| Square root | 145.406327 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 105 |
| Scientific notation | 2.1143 × |
21143 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and forty-three |
| Binary (base 2) | 101001010010111 |
| Octal (base 8) | 51227 |
| Hexadecimal (base 16) | 5297 |
| Base 3 | 1002000002 |
| As time | 21143 seconds = 5 h 52 min 23 s |
Is 21143 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 3) | 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 3) | 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 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 3) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | 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 21143 a prime number?
Yes. 21143 is divisible only by 1 and itself.
What are the factors of 21143?
1, 21143.
What is 21143 in binary?
101001010010111 (hexadecimal 5297, octal 51227).
What is the square root of 21143?
About 145.4063.
Is 21143 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 21143?
21143 is the 2376th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.