The number 1555
1555 is a composite number with 4 divisors. Its prime factorisation is 5 × 311. Divisors (4): 1, 5, 311, 1555.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1555: a semiprime: 5 × 311, the product of two primes.
- 2
1555 is composite. Its prime factorisation is
- 3
The divisors add up to 1872; without 1555 itself that is 317, so 1555 is deficient (317 is less than 1555). Euler's totient φ(1555) = 1240 numbers up to 1555 share no factor with it.
- 4
The digits of 1555 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 34 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1555 = 5 \times 311 \]
1555 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 1872 |
| Euler totient φ(n) | 1240 |
| Square | 2418025 |
| Cube | 3760028875 |
| Square root | 39.433488 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 34 |
| Scientific notation | 1.555 × |
1555 in other forms
| Form | Value |
|---|---|
| In words | one thousand five hundred and fifty-five |
| Roman numerals | MDLV |
| Binary (base 2) | 11000010011 |
| Octal (base 8) | 3023 |
| Hexadecimal (base 16) | 613 |
| Base 3 | 2010121 |
| As time | 1555 seconds = 25 min 55 s |
Is 1555 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 (1555 ÷ 5 = 311) | 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 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 | 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 4) | 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 1555 a prime number?
No. 1555 = 5 × 311, so it is divisible by 5.
What are the factors of 1555?
1, 5, 311, 1555.
What is 1555 in binary?
11000010011 (hexadecimal 613, octal 3023).
What is the square root of 1555?
About 39.4335.
What is 1555 in Roman numerals?
MDLV.
Is 1555 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 1555?
1555 is a semiprime: 5 × 311, the product of two primes.