The number 7985
7985 is a composite number with 4 divisors. Its prime factorisation is 5 × 1597. Divisors (4): 1, 5, 1597, 7985.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 7985: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 5 × 1597, the product of two primes.
- 2
7985 is composite. Its prime factorisation is
- 3
The divisors add up to 9588; without 7985 itself that is 1603, so 7985 is deficient (1603 is less than 7985). Euler's totient φ(7985) = 6384 numbers up to 7985 share no factor with it.
- 4
The digits of 7985 add up to 29, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 52 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7985 = 5 \times 1597 \]
7985 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 9588 |
| Euler totient φ(n) | 6384 |
| Square | 63760225 |
| Cube | 509125396625 |
| Square root | 89.358827 |
| Digit sum / digital root | 29 / 2 |
| Collatz steps to 1 | 52 |
| Scientific notation | 7.985 × |
7985 in other forms
| Form | Value |
|---|---|
| In words | seven thousand nine hundred and eighty-five |
| Binary (base 2) | 1111100110001 |
| Octal (base 8) | 17461 |
| Hexadecimal (base 16) | 1F31 |
| Base 3 | 101221202 |
| As time | 7985 seconds = 2 h 13 min 5 s |
Is 7985 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 | Yes (7985 ÷ 5 = 1597) | 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 5) | 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 2) | 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 10) | 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 7985 a prime number?
No. 7985 = 5 × 1597, so it is divisible by 5.
What are the factors of 7985?
1, 5, 1597, 7985.
What is 7985 in binary?
1111100110001 (hexadecimal 1F31, octal 17461).
What is the square root of 7985?
About 89.3588.
Is 7985 divisible by 3?
No. Its digits add up to 29, which is not a multiple of 3.
What is special about the number 7985?
7985 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 5 × 1597, the product of two primes.