The number 9985
9985 is a composite number with 4 divisors. Its prime factorisation is 5 × 1997. Divisors (4): 1, 5, 1997, 9985.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 9985: a semiprime: 5 × 1997, the product of two primes.
- 2
9985 is composite. Its prime factorisation is
- 3
The divisors add up to 11988; without 9985 itself that is 2003, so 9985 is deficient (2003 is less than 9985). Euler's totient φ(9985) = 7984 numbers up to 9985 share no factor with it.
- 4
The digits of 9985 add up to 31, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 91 steps to reach 1.
LaTeX source of the formulas on this page
\[ 9985 = 5 \times 1997 \]
9985 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 11988 |
| Euler totient φ(n) | 7984 |
| Square | 99700225 |
| Cube | 995506746625 |
| Square root | 99.924972 |
| Digit sum / digital root | 31 / 4 |
| Collatz steps to 1 | 91 |
| Scientific notation | 9.985 × |
9985 in other forms
| Form | Value |
|---|---|
| In words | nine thousand nine hundred and eighty-five |
| Binary (base 2) | 10011100000001 |
| Octal (base 8) | 23401 |
| Hexadecimal (base 16) | 2701 |
| Base 3 | 111200211 |
| As time | 9985 seconds = 2 h 46 min 25 s |
Is 9985 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 1) | 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 | Yes (9985 ÷ 5 = 1997) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 9985 a prime number?
No. 9985 = 5 × 1997, so it is divisible by 5.
What are the factors of 9985?
1, 5, 1997, 9985.
What is 9985 in binary?
10011100000001 (hexadecimal 2701, octal 23401).
What is the square root of 9985?
About 99.9250.
Is 9985 divisible by 3?
No. Its digits add up to 31, which is not a multiple of 3.
What is special about the number 9985?
9985 is a semiprime: 5 × 1997, the product of two primes.