The number 21089
21089 is the 2371st prime number. Its only divisors are 1 and 21089.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21089: the 2371st prime number.
- 2
21089 is prime, so its only factors are 1 and 21089. It is the 2371st prime; the next prime is 21101 and the one before is 21067.
- 3
The divisors add up to 21090; without 21089 itself that is 1, so 21089 is deficient (1 is less than 21089). Euler's totient φ(21089) = 21088 numbers up to 21089 share no factor with it.
- 4
The digits of 21089 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 43 steps to reach 1.
21089 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21090 |
| Euler totient φ(n) | 21088 |
| Square | 444745921 |
| Cube | 9379246727969 |
| Square root | 145.220522 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 43 |
| Scientific notation | 2.1089 × |
21089 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand and eighty-nine |
| Binary (base 2) | 101001001100001 |
| Octal (base 8) | 51141 |
| Hexadecimal (base 16) | 5261 |
| Base 3 | 1001221002 |
| As time | 21089 seconds = 5 h 51 min 29 s |
Is 21089 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 4) | 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 5) | 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 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | 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 21089 a prime number?
Yes. 21089 is divisible only by 1 and itself.
What are the factors of 21089?
1, 21089.
What is 21089 in binary?
101001001100001 (hexadecimal 5261, octal 51141).
What is the square root of 21089?
About 145.2205.
Is 21089 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 21089?
21089 is the 2371st prime number.