The number 20720
20720 is a composite number with 40 divisors. Its prime factorisation is × 5 × 7 × 37. Divisors (40): 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 37, 40, 56, 70 … 20720.
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How to work it out
- 1
20720 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
20720 is composite. Its prime factorisation is
- 3
The divisors add up to 56544; without 20720 itself that is 35824, so 20720 is abundant (35824 is more than 20720). Euler's totient φ(20720) = 6912 numbers up to 20720 share no factor with it.
- 4
The digits of 20720 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 43 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20720 = 2^{4} \times 5 \times 7 \times 37 \]20720 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 40 |
| Sum of divisors | 56544 |
| Euler totient φ(n) | 6912 |
| Square | 429318400 |
| Cube | 8895477248000 |
| Square root | 143.944434 (= 4√1295) |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 43 |
| Scientific notation | 2.072 × |
20720 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand seven hundred and twenty |
| Binary (base 2) | 101000011110000 |
| Octal (base 8) | 50360 |
| Hexadecimal (base 16) | 50F0 |
| Base 3 | 1001102102 |
| As time | 20720 seconds = 5 h 45 min 20 s |
Is 20720 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (20720 ÷ 2 = 10360) | 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 | Yes (20720 ÷ 4 = 5180) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (20720 ÷ 5 = 4144) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (20720 ÷ 7 = 2960) | 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 | Yes (20720 ÷ 8 = 2590) | 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 | Yes (20720 ÷ 10 = 2072) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 20720 a prime number?
No. 20720 = × 5 × 7 × 37, so it is divisible by 2.
What are the factors of 20720?
1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 37, 40, 56, 70, 74, 80, 112, 140, 148, 185, 259, 280, 296, 370, 518, 560, 592, 740, 1036, 1295, 1480, 2072, 2590, 2960, 4144, 5180, 10360, 20720.
What is 20720 in binary?
101000011110000 (hexadecimal 50F0, octal 50360).
What is the square root of 20720?
About 143.9444, exactly 4√1295.
Is 20720 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 20720?
It is a composite number with 40 divisors.