The number 8005
8005 is a composite number with 4 divisors. Its prime factorisation is 5 × 1601. Divisors (4): 1, 5, 1601, 8005.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 8005: a semiprime: 5 × 1601, the product of two primes.
- 2
8005 is composite. Its prime factorisation is
- 3
The divisors add up to 9612; without 8005 itself that is 1607, so 8005 is deficient (1607 is less than 8005). Euler's totient φ(8005) = 6400 numbers up to 8005 share no factor with it.
- 4
The digits of 8005 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 52 steps to reach 1.
LaTeX source of the formulas on this page
\[ 8005 = 5 \times 1601 \]
8005 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 9612 |
| Euler totient φ(n) | 6400 |
| Square | 64080025 |
| Cube | 512960600125 |
| Square root | 89.470666 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 52 |
| Scientific notation | 8.005 × |
8005 in other forms
| Form | Value |
|---|---|
| In words | eight thousand and five |
| Binary (base 2) | 1111101000101 |
| Octal (base 8) | 17505 |
| Hexadecimal (base 16) | 1F45 |
| Base 3 | 101222111 |
| As time | 8005 seconds = 2 h 13 min 25 s |
Is 8005 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 (8005 ÷ 5 = 1601) | 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 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 5) | 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 8005 a prime number?
No. 8005 = 5 × 1601, so it is divisible by 5.
What are the factors of 8005?
1, 5, 1601, 8005.
What is 8005 in binary?
1111101000101 (hexadecimal 1F45, octal 17505).
What is the square root of 8005?
About 89.4707.
Is 8005 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 8005?
8005 is a semiprime: 5 × 1601, the product of two primes.