The number 47981
47981 is the 4946th prime number. Its only divisors are 1 and 47981.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 47981: the 4946th prime number.
- 2
47981 is prime, so its only factors are 1 and 47981. It is the 4946th prime; the next prime is 48017 and the one before is 47977.
- 3
The divisors add up to 47982; without 47981 itself that is 1, so 47981 is deficient (1 is less than 47981). Euler's totient φ(47981) = 47980 numbers up to 47981 share no factor with it.
- 4
The digits of 47981 add up to 29, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 189 steps to reach 1.
47981 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 47982 |
| Euler totient φ(n) | 47980 |
| Square | 2302176361 |
| Cube | 110460723977141 |
| Square root | 219.045657 |
| Digit sum / digital root | 29 / 2 |
| Collatz steps to 1 | 189 |
| Scientific notation | 4.7981 × |
47981 in other forms
| Form | Value |
|---|---|
| In words | forty-seven thousand nine hundred and eighty-one |
| Binary (base 2) | 1011101101101101 |
| Octal (base 8) | 135555 |
| Hexadecimal (base 16) | BB6D |
| Base 3 | 2102211002 |
| As time | 47981 seconds = 13 h 19 min 41 s |
Is 47981 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | 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 10) | 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 47981 a prime number?
Yes. 47981 is divisible only by 1 and itself.
What are the factors of 47981?
1, 47981.
What is 47981 in binary?
1011101101101101 (hexadecimal BB6D, octal 135555).
What is the square root of 47981?
About 219.0457.
Is 47981 divisible by 3?
No. Its digits add up to 29, which is not a multiple of 3.
What is special about the number 47981?
47981 is the 4946th prime number.