The number 31513
31513 is a palindromic prime: it reads the same backwards and is prime, a twin prime (31511 and 31513 are both prime) and the 3391st prime number. Its only divisors are 1 and 31513.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31513: a palindromic prime: it reads the same backwards and is prime; a twin prime (31511 and 31513 are both prime); the 3391st prime number; a palindrome: it reads 31513 backwards too.
- 2
31513 is prime, so its only factors are 1 and 31513. It is the 3391st prime; the next prime is 31517 and the one before is 31511.
- 3
The divisors add up to 31514; without 31513 itself that is 1, so 31513 is deficient (1 is less than 31513). Euler's totient φ(31513) = 31512 numbers up to 31513 share no factor with it.
- 4
The digits of 31513 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 85 steps to reach 1.
31513 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 31514 |
| Euler totient φ(n) | 31512 |
| Square | 993069169 |
| Cube | 31294588722697 |
| Square root | 177.519013 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 85 |
| Scientific notation | 3.1513 × |
31513 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand five hundred and thirteen |
| Binary (base 2) | 111101100011001 |
| Octal (base 8) | 75431 |
| Hexadecimal (base 16) | 7B19 |
| Base 3 | 1121020011 |
| As time | 31513 seconds = 8 h 45 min 13 s |
Is 31513 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 1) | 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 3) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 3) | 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 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31513 a prime number?
Yes. 31513 is divisible only by 1 and itself.
What are the factors of 31513?
1, 31513.
What is 31513 in binary?
111101100011001 (hexadecimal 7B19, octal 75431).
What is the square root of 31513?
About 177.5190.
Is 31513 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 31513?
31513 is a palindromic prime: it reads the same backwards and is prime; a twin prime (31511 and 31513 are both prime); the 3391st prime number; a palindrome: it reads 31513 backwards too.