The number 245
245 is a composite number with 6 divisors. Its prime factorisation is 5 × . Divisors (6): 1, 5, 7, 35, 49, 245.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
245 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
245 is composite. Its prime factorisation is
- 3
The divisors add up to 342; without 245 itself that is 97, so 245 is deficient (97 is less than 245). Euler's totient φ(245) = 168 numbers up to 245 share no factor with it.
- 4
The digits of 245 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 21 steps to reach 1.
LaTeX source of the formulas on this page
\[ 245 = 5 \times 7^{2} \]245 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 342 |
| Euler totient φ(n) | 168 |
| Square | 60025 |
| Cube | 14706125 |
| Square root | 15.652476 (= 7√5) |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 21 |
| Scientific notation | 2.45 × |
245 in other forms
| Form | Value |
|---|---|
| In words | two hundred and forty-five |
| Roman numerals | CCXLV |
| Binary (base 2) | 11110101 |
| Octal (base 8) | 365 |
| Hexadecimal (base 16) | F5 |
| Base 3 | 100002 |
| As time | 245 seconds = 4 min 5 s |
Is 245 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 | Yes (245 ÷ 5 = 49) | 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 | Yes (245 ÷ 7 = 35) | 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 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | 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 245 a prime number?
No. 245 = 5 × , so it is divisible by 5.
What are the factors of 245?
1, 5, 7, 35, 49, 245.
What is 245 in binary?
11110101 (hexadecimal F5, octal 365).
What is the square root of 245?
About 15.6525, exactly 7√5.
What is 245 in Roman numerals?
CCXLV.
Is 245 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 245?
It is a composite number with 6 divisors.