The number 115
115 is a composite number with 4 divisors. Its prime factorisation is 5 × 23. Divisors (4): 1, 5, 23, 115.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 115: a semiprime: 5 × 23, the product of two primes.
- 2
115 is composite. Its prime factorisation is
- 3
The divisors add up to 144; without 115 itself that is 29, so 115 is deficient (29 is less than 115). Euler's totient φ(115) = 88 numbers up to 115 share no factor with it.
- 4
The digits of 115 add up to 7, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 33 steps to reach 1.
LaTeX source of the formulas on this page
\[ 115 = 5 \times 23 \]
115 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 144 |
| Euler totient φ(n) | 88 |
| Square | 13225 |
| Cube | 1520875 |
| Square root | 10.723805 |
| Digit sum / digital root | 7 / 7 |
| Collatz steps to 1 | 33 |
| Scientific notation | 1.15 × |
115 in other forms
| Form | Value |
|---|---|
| In words | one hundred and fifteen |
| Roman numerals | CXV |
| Binary (base 2) | 1110011 |
| Octal (base 8) | 163 |
| Hexadecimal (base 16) | 73 |
| Base 3 | 11021 |
| As time | 115 seconds = 1 min 55 s |
Is 115 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 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (115 ÷ 5 = 23) | 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 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 115 a prime number?
No. 115 = 5 × 23, so it is divisible by 5.
What are the factors of 115?
1, 5, 23, 115.
What is 115 in binary?
1110011 (hexadecimal 73, octal 163).
What is the square root of 115?
About 10.7238.
What is 115 in Roman numerals?
CXV.
Is 115 divisible by 3?
No. Its digits add up to 7, which is not a multiple of 3.
What is special about the number 115?
115 is a semiprime: 5 × 23, the product of two primes.