The number 131
131 is a palindromic prime: it reads the same backwards and is prime, the 32nd prime number and a palindrome: it reads 131 backwards too. Its only divisors are 1 and 131.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 131: a palindromic prime: it reads the same backwards and is prime; the 32nd prime number; a palindrome: it reads 131 backwards too.
- 2
131 is prime, so its only factors are 1 and 131. It is the 32nd prime; the next prime is 137 and the one before is 127.
- 3
The divisors add up to 132; without 131 itself that is 1, so 131 is deficient (1 is less than 131). Euler's totient φ(131) = 130 numbers up to 131 share no factor with it.
- 4
The digits of 131 add up to 5, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 28 steps to reach 1.
131 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 132 |
| Euler totient φ(n) | 130 |
| Square | 17161 |
| Cube | 2248091 |
| Square root | 11.445523 |
| Digit sum / digital root | 5 / 5 |
| Collatz steps to 1 | 28 |
| Scientific notation | 1.31 × |
131 in other forms
| Form | Value |
|---|---|
| In words | one hundred and thirty-one |
| Roman numerals | CXXXI |
| Binary (base 2) | 10000011 |
| Octal (base 8) | 203 |
| Hexadecimal (base 16) | 83 |
| Base 3 | 11212 |
| As time | 131 seconds = 2 min 11 s |
Is 131 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 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | 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 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 131 a prime number?
Yes. 131 is divisible only by 1 and itself.
What are the factors of 131?
1, 131.
What is 131 in binary?
10000011 (hexadecimal 83, octal 203).
What is the square root of 131?
About 11.4455.
What is 131 in Roman numerals?
CXXXI.
Is 131 divisible by 3?
No. Its digits add up to 5, which is not a multiple of 3.
What is special about the number 131?
131 is a palindromic prime: it reads the same backwards and is prime; the 32nd prime number; a palindrome: it reads 131 backwards too.