The number 845
845 is a composite number with 6 divisors. Its prime factorisation is 5 Ć . Divisors (6): 1, 5, 13, 65, 169, 845.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
845 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
845 is composite. Its prime factorisation is
- 3
The divisors add up to 1098; without 845 itself that is 253, so 845 is deficient (253 is less than 845). Euler's totient Ļ(845) = 624 numbers up to 845 share no factor with it.
- 4
The digits of 845 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 41 steps to reach 1.
LaTeX source of the formulas on this page
\[ 845 = 5 \times 13^{2} \]845 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 1098 |
| Euler totient Ļ(n) | 624 |
| Square | 714025 |
| Cube | 603351125 |
| Square root | 29.068884 (= 13ā5) |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 41 |
| Scientific notation | 8.45 Ć |
845 in other forms
| Form | Value |
|---|---|
| In words | eight hundred and forty-five |
| Roman numerals | DCCCXLV |
| Binary (base 2) | 1101001101 |
| Octal (base 8) | 1515 |
| Hexadecimal (base 16) | 34D |
| Base 3 | 1011022 |
| As time | 845 seconds = 14 min 5 s |
Is 845 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 (845 Ć· 5 = 169) | 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 5) | 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 5) | 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 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 845 a prime number?
No. 845 = 5 Ć , so it is divisible by 5.
What are the factors of 845?
1, 5, 13, 65, 169, 845.
What is 845 in binary?
1101001101 (hexadecimal 34D, octal 1515).
What is the square root of 845?
About 29.0689, exactly 13ā5.
What is 845 in Roman numerals?
DCCCXLV.
Is 845 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 845?
It is a composite number with 6 divisors.