The number 555
555 is a palindrome: it reads 555 backwards too. Its prime factorisation is 3 × 5 × 37. Divisors (8): 1, 3, 5, 15, 37, 111, 185, 555.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 555: a palindrome: it reads 555 backwards too; a Harshad number: divisible by its digit sum 15.
- 2
555 is composite. Its prime factorisation is
- 3
The divisors add up to 912; without 555 itself that is 357, so 555 is deficient (357 is less than 555). Euler's totient φ(555) = 288 numbers up to 555 share no factor with it.
- 4
The digits of 555 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 30 steps to reach 1.
LaTeX source of the formulas on this page
\[ 555 = 3 \times 5 \times 37 \]
555 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 912 |
| Euler totient φ(n) | 288 |
| Square | 308025 |
| Cube | 170953875 |
| Square root | 23.558438 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 30 |
| Scientific notation | 5.55 × |
555 in other forms
| Form | Value |
|---|---|
| In words | five hundred and fifty-five |
| Roman numerals | DLV |
| Binary (base 2) | 1000101011 |
| Octal (base 8) | 1053 |
| Hexadecimal (base 16) | 22B |
| Base 3 | 202120 |
| As time | 555 seconds = 9 min 15 s |
Is 555 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 (555 ÷ 3 = 185) | 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 (555 ÷ 5 = 111) | 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 2) | 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 6) | 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 555 a prime number?
No. 555 = 3 × 5 × 37, so it is divisible by 3.
What are the factors of 555?
1, 3, 5, 15, 37, 111, 185, 555.
What is 555 in binary?
1000101011 (hexadecimal 22B, octal 1053).
What is the square root of 555?
About 23.5584.
What is 555 in Roman numerals?
DLV.
Is 555 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 555?
555 is a palindrome: it reads 555 backwards too; a Harshad number: divisible by its digit sum 15.