The number 389
389 is the 77th prime number. Its only divisors are 1 and 389.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 389: the 77th prime number.
- 2
389 is prime, so its only factors are 1 and 389. It is the 77th prime; the next prime is 397 and the one before is 383.
- 3
The divisors add up to 390; without 389 itself that is 1, so 389 is deficient (1 is less than 389). Euler's totient φ(389) = 388 numbers up to 389 share no factor with it.
- 4
The digits of 389 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 120 steps to reach 1.
389 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 390 |
| Euler totient φ(n) | 388 |
| Square | 151321 |
| Cube | 58863869 |
| Square root | 19.723083 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 120 |
| Scientific notation | 3.89 × |
389 in other forms
| Form | Value |
|---|---|
| In words | three hundred and eighty-nine |
| Roman numerals | CCCLXXXIX |
| Binary (base 2) | 110000101 |
| Octal (base 8) | 605 |
| Hexadecimal (base 16) | 185 |
| Base 3 | 112102 |
| As time | 389 seconds = 6 min 29 s |
Is 389 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 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 5) | 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 4) | 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 389 a prime number?
Yes. 389 is divisible only by 1 and itself.
What are the factors of 389?
1, 389.
What is 389 in binary?
110000101 (hexadecimal 185, octal 605).
What is the square root of 389?
About 19.7231.
What is 389 in Roman numerals?
CCCLXXXIX.
Is 389 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 389?
389 is the 77th prime number.