The number 2745
2745 is a composite number with 12 divisors. Its prime factorisation is × 5 × 61. Divisors (12): 1, 3, 5, 9, 15, 45, 61, 183, 305, 549, 915, 2745.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 2745: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
2745 is composite. Its prime factorisation is
- 3
The divisors add up to 4836; without 2745 itself that is 2091, so 2745 is deficient (2091 is less than 2745). Euler's totient φ(2745) = 1440 numbers up to 2745 share no factor with it.
- 4
The digits of 2745 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 40 steps to reach 1.
LaTeX source of the formulas on this page
\[ 2745 = 3^{2} \times 5 \times 61 \]2745 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 4836 |
| Euler totient φ(n) | 1440 |
| Square | 7535025 |
| Cube | 20683643625 |
| Square root | 52.392748 (= 3√305) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 40 |
| Scientific notation | 2.745 × |
2745 in other forms
| Form | Value |
|---|---|
| In words | two thousand seven hundred and forty-five |
| Roman numerals | MMDCCXLV |
| Binary (base 2) | 101010111001 |
| Octal (base 8) | 5271 |
| Hexadecimal (base 16) | AB9 |
| Base 3 | 10202200 |
| As time | 2745 seconds = 45 min 45 s |
Is 2745 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 (2745 ÷ 3 = 915) | 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 (2745 ÷ 5 = 549) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (2745 ÷ 9 = 305) | 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 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 2745 a prime number?
No. 2745 = × 5 × 61, so it is divisible by 3.
What are the factors of 2745?
1, 3, 5, 9, 15, 45, 61, 183, 305, 549, 915, 2745.
What is 2745 in binary?
101010111001 (hexadecimal AB9, octal 5271).
What is the square root of 2745?
About 52.3927, exactly 3√305.
What is 2745 in Roman numerals?
MMDCCXLV.
Is 2745 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 2745?
2745 is a happy number: repeatedly adding the squares of its digits reaches 1.