The number 38721
38721 is a composite number with 4 divisors. Its prime factorisation is 3 × 12907. Divisors (4): 1, 3, 12907, 38721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 38721: a semiprime: 3 × 12907, the product of two primes.
- 2
38721 is composite. Its prime factorisation is
- 3
The divisors add up to 51632; without 38721 itself that is 12911, so 38721 is deficient (12911 is less than 38721). Euler's totient φ(38721) = 25812 numbers up to 38721 share no factor with it.
- 4
The digits of 38721 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 62 steps to reach 1.
LaTeX source of the formulas on this page
\[ 38721 = 3 \times 12907 \]
38721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 51632 |
| Euler totient φ(n) | 25812 |
| Square | 1499315841 |
| Cube | 58055008679361 |
| Square root | 196.776523 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 62 |
| Scientific notation | 3.8721 × |
38721 in other forms
| Form | Value |
|---|---|
| In words | thirty-eight thousand seven hundred and twenty-one |
| Binary (base 2) | 1001011101000001 |
| Octal (base 8) | 113501 |
| Hexadecimal (base 16) | 9741 |
| Base 3 | 1222010010 |
| As time | 38721 seconds = 10 h 45 min 21 s |
Is 38721 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 (38721 ÷ 3 = 12907) | 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 | No (remainder 4) | 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 1) | 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 38721 a prime number?
No. 38721 = 3 × 12907, so it is divisible by 3.
What are the factors of 38721?
1, 3, 12907, 38721.
What is 38721 in binary?
1001011101000001 (hexadecimal 9741, octal 113501).
What is the square root of 38721?
About 196.7765.
Is 38721 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 38721?
38721 is a semiprime: 3 × 12907, the product of two primes.