The number 20091
20091 is a composite number with 8 divisors. Its prime factorisation is 3 × 37 × 181. Divisors (8): 1, 3, 37, 111, 181, 543, 6697, 20091.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20091: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
20091 is composite. Its prime factorisation is
- 3
The divisors add up to 27664; without 20091 itself that is 7573, so 20091 is deficient (7573 is less than 20091). Euler's totient φ(20091) = 12960 numbers up to 20091 share no factor with it.
- 4
The digits of 20091 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 43 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20091 = 3 \times 37 \times 181 \]
20091 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 27664 |
| Euler totient φ(n) | 12960 |
| Square | 403648281 |
| Cube | 8109697613571 |
| Square root | 141.742725 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 43 |
| Scientific notation | 2.0091 × |
20091 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand and ninety-one |
| Binary (base 2) | 100111001111011 |
| Octal (base 8) | 47173 |
| Hexadecimal (base 16) | 4E7B |
| Base 3 | 1000120010 |
| As time | 20091 seconds = 5 h 34 min 51 s |
Is 20091 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 | Yes (20091 ÷ 3 = 6697) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | 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 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | 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 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 20091 a prime number?
No. 20091 = 3 × 37 × 181, so it is divisible by 3.
What are the factors of 20091?
1, 3, 37, 111, 181, 543, 6697, 20091.
What is 20091 in binary?
100111001111011 (hexadecimal 4E7B, octal 47173).
What is the square root of 20091?
About 141.7427.
Is 20091 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 20091?
20091 is a happy number: repeatedly adding the squares of its digits reaches 1.