The number 3987
3987 is a composite number with 6 divisors. Its prime factorisation is × 443. Divisors (6): 1, 3, 9, 443, 1329, 3987.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 3987: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
3987 is composite. Its prime factorisation is
- 3
The divisors add up to 5772; without 3987 itself that is 1785, so 3987 is deficient (1785 is less than 3987). Euler's totient φ(3987) = 2652 numbers up to 3987 share no factor with it.
- 4
The digits of 3987 add up to 27, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 51 steps to reach 1.
LaTeX source of the formulas on this page
\[ 3987 = 3^{2} \times 443 \]3987 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 5772 |
| Euler totient φ(n) | 2652 |
| Square | 15896169 |
| Cube | 63378025803 |
| Square root | 63.142696 (= 3√443) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 51 |
| Scientific notation | 3.987 × |
3987 in other forms
| Form | Value |
|---|---|
| In words | three thousand nine hundred and eighty-seven |
| Roman numerals | MMMCMLXXXVII |
| Binary (base 2) | 111110010011 |
| Octal (base 8) | 7623 |
| Hexadecimal (base 16) | F93 |
| Base 3 | 12110200 |
| As time | 3987 seconds = 1 h 6 min 27 s |
Is 3987 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 (3987 ÷ 3 = 1329) | 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 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (3987 ÷ 9 = 443) | 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 5) | 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 3987 a prime number?
No. 3987 = × 443, so it is divisible by 3.
What are the factors of 3987?
1, 3, 9, 443, 1329, 3987.
What is 3987 in binary?
111110010011 (hexadecimal F93, octal 7623).
What is the square root of 3987?
About 63.1427, exactly 3√443.
What is 3987 in Roman numerals?
MMMCMLXXXVII.
Is 3987 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 3987?
3987 is a happy number: repeatedly adding the squares of its digits reaches 1.