The number 20001
20001 is a composite number with 8 divisors. Its prime factorisation is 3 × 59 × 113. Divisors (8): 1, 3, 59, 113, 177, 339, 6667, 20001.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20001: a Harshad number: divisible by its digit sum 3.
- 2
20001 is composite. Its prime factorisation is
- 3
The divisors add up to 27360; without 20001 itself that is 7359, so 20001 is deficient (7359 is less than 20001). Euler's totient φ(20001) = 12992 numbers up to 20001 share no factor with it.
- 4
The digits of 20001 add up to 3, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 167 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20001 = 3 \times 59 \times 113 \]
20001 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 27360 |
| Euler totient φ(n) | 12992 |
| Square | 400040001 |
| Cube | 8001200060001 |
| Square root | 141.424892 |
| Digit sum / digital root | 3 / 3 |
| Collatz steps to 1 | 167 |
| Scientific notation | 2.0001 × |
20001 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand and one |
| Binary (base 2) | 100111000100001 |
| Octal (base 8) | 47041 |
| Hexadecimal (base 16) | 4E21 |
| Base 3 | 1000102210 |
| As time | 20001 seconds = 5 h 33 min 21 s |
Is 20001 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 (20001 ÷ 3 = 6667) | 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 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 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 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 20001 a prime number?
No. 20001 = 3 × 59 × 113, so it is divisible by 3.
What are the factors of 20001?
1, 3, 59, 113, 177, 339, 6667, 20001.
What is 20001 in binary?
100111000100001 (hexadecimal 4E21, octal 47041).
What is the square root of 20001?
About 141.4249.
Is 20001 divisible by 3?
Yes. Its digits add up to 3, a multiple of 3.
What is special about the number 20001?
20001 is a Harshad number: divisible by its digit sum 3.