The number 67721
67721 is a composite number with 4 divisors. Its prime factorisation is 241 × 281. Divisors (4): 1, 241, 281, 67721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 67721: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 241 × 281, the product of two primes.
- 2
67721 is composite. Its prime factorisation is
- 3
The divisors add up to 68244; without 67721 itself that is 523, so 67721 is deficient (523 is less than 67721). Euler's totient φ(67721) = 67200 numbers up to 67721 share no factor with it.
- 4
The digits of 67721 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 205 steps to reach 1.
LaTeX source of the formulas on this page
\[ 67721 = 241 \times 281 \]
67721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 68244 |
| Euler totient φ(n) | 67200 |
| Square | 4586133841 |
| Cube | 310577569846361 |
| Square root | 260.232588 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 205 |
| Scientific notation | 6.7721 × |
67721 in other forms
| Form | Value |
|---|---|
| In words | sixty-seven thousand seven hundred and twenty-one |
| Binary (base 2) | 10000100010001001 |
| Octal (base 8) | 204211 |
| Hexadecimal (base 16) | 10889 |
| Base 3 | 10102220012 |
| As time | 67721 seconds = 18 h 48 min 41 s |
Is 67721 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 2) | 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 5) | 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 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 67721 a prime number?
No. 67721 = 241 × 281, so it is divisible by 241.
What are the factors of 67721?
1, 241, 281, 67721.
What is 67721 in binary?
10000100010001001 (hexadecimal 10889, octal 204211).
What is the square root of 67721?
About 260.2326.
Is 67721 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 67721?
67721 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 241 × 281, the product of two primes.