The number 20081
20081 is a composite number with 4 divisors. Its prime factorisation is 43 × 467. Divisors (4): 1, 43, 467, 20081.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20081: a semiprime: 43 × 467, the product of two primes.
- 2
20081 is composite. Its prime factorisation is
- 3
The divisors add up to 20592; without 20081 itself that is 511, so 20081 is deficient (511 is less than 20081). Euler's totient φ(20081) = 19572 numbers up to 20081 share no factor with it.
- 4
The digits of 20081 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 136 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20081 = 43 \times 467 \]
20081 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 20592 |
| Euler totient φ(n) | 19572 |
| Square | 403246561 |
| Cube | 8097594191441 |
| Square root | 141.707445 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 136 |
| Scientific notation | 2.0081 × |
20081 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand and eighty-one |
| Binary (base 2) | 100111001110001 |
| Octal (base 8) | 47161 |
| Hexadecimal (base 16) | 4E71 |
| Base 3 | 1000112202 |
| As time | 20081 seconds = 5 h 34 min 41 s |
Is 20081 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 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | 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 20081 a prime number?
No. 20081 = 43 × 467, so it is divisible by 43.
What are the factors of 20081?
1, 43, 467, 20081.
What is 20081 in binary?
100111001110001 (hexadecimal 4E71, octal 47161).
What is the square root of 20081?
About 141.7074.
Is 20081 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 20081?
20081 is a semiprime: 43 × 467, the product of two primes.