The number 31481
31481 is the 3388th prime number. Its only divisors are 1 and 31481.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31481: the 3388th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
31481 is prime, so its only factors are 1 and 31481. It is the 3388th prime; the next prime is 31489 and the one before is 31477.
- 3
The divisors add up to 31482; without 31481 itself that is 1, so 31481 is deficient (1 is less than 31481). Euler's totient φ(31481) = 31480 numbers up to 31481 share no factor with it.
- 4
The digits of 31481 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 85 steps to reach 1.
31481 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 31482 |
| Euler totient φ(n) | 31480 |
| Square | 991053361 |
| Cube | 31199350857641 |
| Square root | 177.428859 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 85 |
| Scientific notation | 3.1481 × |
31481 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand four hundred and eighty-one |
| Binary (base 2) | 111101011111001 |
| Octal (base 8) | 75371 |
| Hexadecimal (base 16) | 7AF9 |
| Base 3 | 1121011222 |
| As time | 31481 seconds = 8 h 44 min 41 s |
Is 31481 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 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 8) | 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 31481 a prime number?
Yes. 31481 is divisible only by 1 and itself.
What are the factors of 31481?
1, 31481.
What is 31481 in binary?
111101011111001 (hexadecimal 7AF9, octal 75371).
What is the square root of 31481?
About 177.4289.
Is 31481 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 31481?
31481 is the 3388th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.