The number 18987
18987 is a composite number with 4 divisors. Its prime factorisation is 3 × 6329. Divisors (4): 1, 3, 6329, 18987.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 18987: a semiprime: 3 × 6329, the product of two primes.
- 2
18987 is composite. Its prime factorisation is
- 3
The divisors add up to 25320; without 18987 itself that is 6333, so 18987 is deficient (6333 is less than 18987). Euler's totient φ(18987) = 12656 numbers up to 18987 share no factor with it.
- 4
The digits of 18987 add up to 33, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 154 steps to reach 1.
LaTeX source of the formulas on this page
\[ 18987 = 3 \times 6329 \]
18987 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 25320 |
| Euler totient φ(n) | 12656 |
| Square | 360506169 |
| Cube | 6844930630803 |
| Square root | 137.793323 |
| Digit sum / digital root | 33 / 6 |
| Collatz steps to 1 | 154 |
| Scientific notation | 1.8987 × |
18987 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand nine hundred and eighty-seven |
| Binary (base 2) | 100101000101011 |
| Octal (base 8) | 45053 |
| Hexadecimal (base 16) | 4A2B |
| Base 3 | 222001020 |
| As time | 18987 seconds = 5 h 16 min 27 s |
Is 18987 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 (18987 ÷ 3 = 6329) | 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 3) | 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 | No (remainder 6) | 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 1) | 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 18987 a prime number?
No. 18987 = 3 × 6329, so it is divisible by 3.
What are the factors of 18987?
1, 3, 6329, 18987.
What is 18987 in binary?
100101000101011 (hexadecimal 4A2B, octal 45053).
What is the square root of 18987?
About 137.7933.
Is 18987 divisible by 3?
Yes. Its digits add up to 33, a multiple of 3.
What is special about the number 18987?
18987 is a semiprime: 3 × 6329, the product of two primes.