The number 7155
7155 is a composite number with 16 divisors. Its prime factorisation is × 5 × 53. Divisors (16): 1, 3, 5, 9, 15, 27, 45, 53, 135, 159, 265, 477, 795, 1431, 2385, 7155.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 7155: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
7155 is composite. Its prime factorisation is
- 3
The divisors add up to 12960; without 7155 itself that is 5805, so 7155 is deficient (5805 is less than 7155). Euler's totient φ(7155) = 3744 numbers up to 7155 share no factor with it.
- 4
The digits of 7155 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 75 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7155 = 3^{3} \times 5 \times 53 \]7155 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 12960 |
| Euler totient φ(n) | 3744 |
| Square | 51194025 |
| Cube | 366293248875 |
| Square root | 84.587233 (= 3√795) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 75 |
| Scientific notation | 7.155 × |
7155 in other forms
| Form | Value |
|---|---|
| In words | seven thousand one hundred and fifty-five |
| Binary (base 2) | 1101111110011 |
| Octal (base 8) | 15763 |
| Hexadecimal (base 16) | 1BF3 |
| Base 3 | 100211000 |
| As time | 7155 seconds = 1 h 59 min 15 s |
Is 7155 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 | Yes (7155 ÷ 3 = 2385) | 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 (7155 ÷ 5 = 1431) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 | Yes (7155 ÷ 9 = 795) | 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 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 7155 a prime number?
No. 7155 = × 5 × 53, so it is divisible by 3.
What are the factors of 7155?
1, 3, 5, 9, 15, 27, 45, 53, 135, 159, 265, 477, 795, 1431, 2385, 7155.
What is 7155 in binary?
1101111110011 (hexadecimal 1BF3, octal 15763).
What is the square root of 7155?
About 84.5872, exactly 3√795.
Is 7155 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 7155?
7155 is a happy number: repeatedly adding the squares of its digits reaches 1.