The number 20979
20979 is a composite number with 20 divisors. Its prime factorisation is × 7 × 37. Divisors (20): 1, 3, 7, 9, 21, 27, 37, 63, 81, 111, 189, 259, 333, 567, 777, 999 … 20979.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20979: a Harshad number: divisible by its digit sum 27.
- 2
20979 is composite. Its prime factorisation is
- 3
The divisors add up to 36784; without 20979 itself that is 15805, so 20979 is deficient (15805 is less than 20979). Euler's totient φ(20979) = 11664 numbers up to 20979 share no factor with it.
- 4
The digits of 20979 add up to 27, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20979 = 3^{4} \times 7 \times 37 \]20979 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 36784 |
| Euler totient φ(n) | 11664 |
| Square | 440118441 |
| Cube | 9233244773739 |
| Square root | 144.841292 (= 9√259) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.0979 × |
20979 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand nine hundred and seventy-nine |
| Binary (base 2) | 101000111110011 |
| Octal (base 8) | 50763 |
| Hexadecimal (base 16) | 51F3 |
| Base 3 | 1001210000 |
| As time | 20979 seconds = 5 h 49 min 39 s |
Is 20979 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 (20979 ÷ 3 = 6993) | 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 4) | 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 | Yes (20979 ÷ 7 = 2997) | 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 | Yes (20979 ÷ 9 = 2331) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 9) | 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 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 20979 a prime number?
No. 20979 = × 7 × 37, so it is divisible by 3.
What are the factors of 20979?
1, 3, 7, 9, 21, 27, 37, 63, 81, 111, 189, 259, 333, 567, 777, 999, 2331, 2997, 6993, 20979.
What is 20979 in binary?
101000111110011 (hexadecimal 51F3, octal 50763).
What is the square root of 20979?
About 144.8413, exactly 9√259.
Is 20979 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 20979?
20979 is a Harshad number: divisible by its digit sum 27.