The number 47991
47991 is a composite number with 8 divisors. Its prime factorisation is 3 × 17 × 941. Divisors (8): 1, 3, 17, 51, 941, 2823, 15997, 47991.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
47991 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
47991 is composite. Its prime factorisation is
- 3
The divisors add up to 67824; without 47991 itself that is 19833, so 47991 is deficient (19833 is less than 47991). Euler's totient φ(47991) = 30080 numbers up to 47991 share no factor with it.
- 4
The digits of 47991 add up to 30, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 189 steps to reach 1.
LaTeX source of the formulas on this page
\[ 47991 = 3 \times 17 \times 941 \]
47991 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 67824 |
| Euler totient φ(n) | 30080 |
| Square | 2303136081 |
| Cube | 110529803663271 |
| Square root | 219.068482 |
| Digit sum / digital root | 30 / 3 |
| Collatz steps to 1 | 189 |
| Scientific notation | 4.7991 × |
47991 in other forms
| Form | Value |
|---|---|
| In words | forty-seven thousand nine hundred and ninety-one |
| Binary (base 2) | 1011101101110111 |
| Octal (base 8) | 135567 |
| Hexadecimal (base 16) | BB77 |
| Base 3 | 2102211110 |
| As time | 47991 seconds = 13 h 19 min 51 s |
Is 47991 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 (47991 ÷ 3 = 15997) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | 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 6) | 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 7) | 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 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 47991 a prime number?
No. 47991 = 3 × 17 × 941, so it is divisible by 3.
What are the factors of 47991?
1, 3, 17, 51, 941, 2823, 15997, 47991.
What is 47991 in binary?
1011101101110111 (hexadecimal BB77, octal 135567).
What is the square root of 47991?
About 219.0685.
Is 47991 divisible by 3?
Yes. Its digits add up to 30, a multiple of 3.
What is special about the number 47991?
It is a composite number with 8 divisors.