The number 20971
20971 is a composite number with 4 divisors. Its prime factorisation is 67 × 313. Divisors (4): 1, 67, 313, 20971.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20971: a semiprime: 67 × 313, the product of two primes.
- 2
20971 is composite. Its prime factorisation is
- 3
The divisors add up to 21352; without 20971 itself that is 381, so 20971 is deficient (381 is less than 20971). Euler's totient φ(20971) = 20592 numbers up to 20971 share no factor with it.
- 4
The digits of 20971 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 87 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20971 = 67 \times 313 \]
20971 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 21352 |
| Euler totient φ(n) | 20592 |
| Square | 439782841 |
| Cube | 9222685958611 |
| Square root | 144.813673 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 87 |
| Scientific notation | 2.0971 × |
20971 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand nine hundred and seventy-one |
| Binary (base 2) | 101000111101011 |
| Octal (base 8) | 50753 |
| Hexadecimal (base 16) | 51EB |
| Base 3 | 1001202201 |
| As time | 20971 seconds = 5 h 49 min 31 s |
Is 20971 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 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 1) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | 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 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 20971 a prime number?
No. 20971 = 67 × 313, so it is divisible by 67.
What are the factors of 20971?
1, 67, 313, 20971.
What is 20971 in binary?
101000111101011 (hexadecimal 51EB, octal 50753).
What is the square root of 20971?
About 144.8137.
Is 20971 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 20971?
20971 is a semiprime: 67 × 313, the product of two primes.