The number 47721
47721 is a composite number with 4 divisors. Its prime factorisation is 3 × 15907. Divisors (4): 1, 3, 15907, 47721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 47721: a semiprime: 3 × 15907, the product of two primes.
- 2
47721 is composite. Its prime factorisation is
- 3
The divisors add up to 63632; without 47721 itself that is 15911, so 47721 is deficient (15911 is less than 47721). Euler's totient φ(47721) = 31812 numbers up to 47721 share no factor with it.
- 4
The digits of 47721 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 127 steps to reach 1.
LaTeX source of the formulas on this page
\[ 47721 = 3 \times 15907 \]
47721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 63632 |
| Euler totient φ(n) | 31812 |
| Square | 2277293841 |
| Cube | 108674739386361 |
| Square root | 218.451368 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 127 |
| Scientific notation | 4.7721 × |
47721 in other forms
| Form | Value |
|---|---|
| In words | forty-seven thousand seven hundred and twenty-one |
| Binary (base 2) | 1011101001101001 |
| Octal (base 8) | 135151 |
| Hexadecimal (base 16) | BA69 |
| Base 3 | 2102110110 |
| As time | 47721 seconds = 13 h 15 min 21 s |
Is 47721 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 (47721 ÷ 3 = 15907) | 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 2) | 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 3) | 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 47721 a prime number?
No. 47721 = 3 × 15907, so it is divisible by 3.
What are the factors of 47721?
1, 3, 15907, 47721.
What is 47721 in binary?
1011101001101001 (hexadecimal BA69, octal 135151).
What is the square root of 47721?
About 218.4514.
Is 47721 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 47721?
47721 is a semiprime: 3 × 15907, the product of two primes.