The number 387
387 is a binary palindrome (110000011). Its prime factorisation is × 43. Divisors (6): 1, 3, 9, 43, 129, 387.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 387: a binary palindrome (110000011).
- 2
387 is composite. Its prime factorisation is
- 3
The divisors add up to 572; without 387 itself that is 185, so 387 is deficient (185 is less than 387). Euler's totient φ(387) = 252 numbers up to 387 share no factor with it.
- 4
The digits of 387 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 120 steps to reach 1.
LaTeX source of the formulas on this page
\[ 387 = 3^{2} \times 43 \]387 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 572 |
| Euler totient φ(n) | 252 |
| Square | 149769 |
| Cube | 57960603 |
| Square root | 19.672316 (= 3√43) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 120 |
| Scientific notation | 3.87 × |
387 in other forms
| Form | Value |
|---|---|
| In words | three hundred and eighty-seven |
| Roman numerals | CCCLXXXVII |
| Binary (base 2) | 110000011 |
| Octal (base 8) | 603 |
| Hexadecimal (base 16) | 183 |
| Base 3 | 112100 |
| As time | 387 seconds = 6 min 27 s |
Is 387 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 | Yes (387 ÷ 3 = 129) | 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 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (387 ÷ 9 = 43) | 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 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 387 a prime number?
No. 387 = × 43, so it is divisible by 3.
What are the factors of 387?
1, 3, 9, 43, 129, 387.
What is 387 in binary?
110000011 (hexadecimal 183, octal 603).
What is the square root of 387?
About 19.6723, exactly 3√43.
What is 387 in Roman numerals?
CCCLXXXVII.
Is 387 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 387?
387 is a binary palindrome (110000011).