The number 7997
7997 is a palindrome: it reads 7997 backwards too. Its prime factorisation is 11 × 727. Divisors (4): 1, 11, 727, 7997.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 7997: a palindrome: it reads 7997 backwards too; a semiprime: 11 × 727, the product of two primes.
- 2
7997 is composite. Its prime factorisation is
- 3
The divisors add up to 8736; without 7997 itself that is 739, so 7997 is deficient (739 is less than 7997). Euler's totient φ(7997) = 7260 numbers up to 7997 share no factor with it.
- 4
The digits of 7997 add up to 32, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 52 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7997 = 11 \times 727 \]
7997 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 8736 |
| Euler totient φ(n) | 7260 |
| Square | 63952009 |
| Cube | 511424215973 |
| Square root | 89.425947 |
| Digit sum / digital root | 32 / 5 |
| Collatz steps to 1 | 52 |
| Scientific notation | 7.997 × |
7997 in other forms
| Form | Value |
|---|---|
| In words | seven thousand nine hundred and ninety-seven |
| Binary (base 2) | 1111100111101 |
| Octal (base 8) | 17475 |
| Hexadecimal (base 16) | 1F3D |
| Base 3 | 101222012 |
| As time | 7997 seconds = 2 h 13 min 17 s |
Is 7997 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 | No (remainder 2) | 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 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | 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 | Yes (7997 ÷ 11 = 727) | 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 7997 a prime number?
No. 7997 = 11 × 727, so it is divisible by 11.
What are the factors of 7997?
1, 11, 727, 7997.
What is 7997 in binary?
1111100111101 (hexadecimal 1F3D, octal 17475).
What is the square root of 7997?
About 89.4259.
Is 7997 divisible by 3?
No. Its digits add up to 32, which is not a multiple of 3.
What is special about the number 7997?
7997 is a palindrome: it reads 7997 backwards too; a semiprime: 11 × 727, the product of two primes.