The number 8021
8021 is a composite number with 4 divisors. Its prime factorisation is 13 × 617. Divisors (4): 1, 13, 617, 8021.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 8021: a semiprime: 13 × 617, the product of two primes.
- 2
8021 is composite. Its prime factorisation is
- 3
The divisors add up to 8652; without 8021 itself that is 631, so 8021 is deficient (631 is less than 8021). Euler's totient φ(8021) = 7392 numbers up to 8021 share no factor with it.
- 4
The digits of 8021 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 114 steps to reach 1.
LaTeX source of the formulas on this page
\[ 8021 = 13 \times 617 \]
8021 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 8652 |
| Euler totient φ(n) | 7392 |
| Square | 64336441 |
| Cube | 516042593261 |
| Square root | 89.560036 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 114 |
| Scientific notation | 8.021 × |
8021 in other forms
| Form | Value |
|---|---|
| In words | eight thousand and twenty-one |
| Binary (base 2) | 1111101010101 |
| Octal (base 8) | 17525 |
| Hexadecimal (base 16) | 1F55 |
| Base 3 | 102000002 |
| As time | 8021 seconds = 2 h 13 min 41 s |
Is 8021 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 1) | 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 6) | 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 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | 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 8021 a prime number?
No. 8021 = 13 × 617, so it is divisible by 13.
What are the factors of 8021?
1, 13, 617, 8021.
What is 8021 in binary?
1111101010101 (hexadecimal 1F55, octal 17525).
What is the square root of 8021?
About 89.5600.
Is 8021 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 8021?
8021 is a semiprime: 13 × 617, the product of two primes.