The number 56721
56721 is a composite number with 16 divisors. Its prime factorisation is 3 × 7 × 37 × 73. Divisors (16): 1, 3, 7, 21, 37, 73, 111, 219, 259, 511, 777, 1533, 2701, 8103, 18907, 56721.
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How to work it out
- 1
What is special about 56721: a Harshad number: divisible by its digit sum 21.
- 2
56721 is composite. Its prime factorisation is
- 3
The divisors add up to 89984; without 56721 itself that is 33263, so 56721 is deficient (33263 is less than 56721). Euler's totient φ(56721) = 31104 numbers up to 56721 share no factor with it.
- 4
The digits of 56721 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 60 steps to reach 1.
LaTeX source of the formulas on this page
\[ 56721 = 3 \times 7 \times 37 \times 73 \]
56721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 89984 |
| Euler totient φ(n) | 31104 |
| Square | 3217271841 |
| Cube | 182486876093361 |
| Square root | 238.161710 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 60 |
| Scientific notation | 5.6721 × |
56721 in other forms
| Form | Value |
|---|---|
| In words | fifty-six thousand seven hundred and twenty-one |
| Binary (base 2) | 1101110110010001 |
| Octal (base 8) | 156621 |
| Hexadecimal (base 16) | DD91 |
| Base 3 | 2212210210 |
| As time | 56721 seconds = 15 h 45 min 21 s |
Is 56721 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 (56721 ÷ 3 = 18907) | 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 | Yes (56721 ÷ 7 = 8103) | 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 5) | 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 56721 a prime number?
No. 56721 = 3 × 7 × 37 × 73, so it is divisible by 3.
What are the factors of 56721?
1, 3, 7, 21, 37, 73, 111, 219, 259, 511, 777, 1533, 2701, 8103, 18907, 56721.
What is 56721 in binary?
1101110110010001 (hexadecimal DD91, octal 156621).
What is the square root of 56721?
About 238.1617.
Is 56721 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 56721?
56721 is a Harshad number: divisible by its digit sum 21.