The number 1289
1289 is a twin prime (1289 and 1291 are both prime) and the 209th prime number. Its only divisors are 1 and 1289.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1289: a twin prime (1289 and 1291 are both prime); the 209th prime number.
- 2
1289 is prime, so its only factors are 1 and 1289. It is the 209th prime; the next prime is 1291 and the one before is 1283.
- 3
The divisors add up to 1290; without 1289 itself that is 1, so 1289 is deficient (1 is less than 1289). Euler's totient φ(1289) = 1288 numbers up to 1289 share no factor with it.
- 4
The digits of 1289 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 145 steps to reach 1.
1289 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 1290 |
| Euler totient φ(n) | 1288 |
| Square | 1661521 |
| Cube | 2141700569 |
| Square root | 35.902646 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 145 |
| Scientific notation | 1.289 × |
1289 in other forms
| Form | Value |
|---|---|
| In words | one thousand two hundred and eighty-nine |
| Roman numerals | MCCLXXXIX |
| Binary (base 2) | 10100001001 |
| Octal (base 8) | 2411 |
| Hexadecimal (base 16) | 509 |
| Base 3 | 1202202 |
| As time | 1289 seconds = 21 min 29 s |
Is 1289 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 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 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 1289 a prime number?
Yes. 1289 is divisible only by 1 and itself.
What are the factors of 1289?
1, 1289.
What is 1289 in binary?
10100001001 (hexadecimal 509, octal 2411).
What is the square root of 1289?
About 35.9026.
What is 1289 in Roman numerals?
MCCLXXXIX.
Is 1289 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 1289?
1289 is a twin prime (1289 and 1291 are both prime); the 209th prime number.