The number 42780
42780 is a composite number with 48 divisors. Its prime factorisation is × 3 × 5 × 23 × 31. Divisors (48): 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 23, 30, 31, 46, 60, 62 … 42780.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 42780: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
42780 is composite. Its prime factorisation is
- 3
The divisors add up to 129024; without 42780 itself that is 86244, so 42780 is abundant (86244 is more than 42780). Euler's totient φ(42780) = 10560 numbers up to 42780 share no factor with it.
- 4
The digits of 42780 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 75 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42780 = 2^{2} \times 3 \times 5 \times 23 \times 31 \]42780 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 48 |
| Sum of divisors | 129024 |
| Euler totient φ(n) | 10560 |
| Square | 1830128400 |
| Cube | 78292892952000 |
| Square root | 206.833266 (= 2√10695) |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 75 |
| Scientific notation | 4.278 × |
42780 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand seven hundred and eighty |
| Binary (base 2) | 1010011100011100 |
| Octal (base 8) | 123434 |
| Hexadecimal (base 16) | A71C |
| Base 3 | 2011200110 |
| As time | 42780 seconds = 11 h 53 min 0 s |
Is 42780 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (42780 ÷ 2 = 21390) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (42780 ÷ 3 = 14260) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (42780 ÷ 4 = 10695) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (42780 ÷ 5 = 8556) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (42780 ÷ 6 = 7130) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (42780 ÷ 10 = 4278) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (42780 ÷ 12 = 3565) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 42780 a prime number?
No. 42780 = × 3 × 5 × 23 × 31, so it is divisible by 2.
What are the factors of 42780?
1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 23, 30, 31, 46, 60, 62, 69, 92, 93, 115, 124, 138, 155, 186, 230, 276, 310, 345, 372, 460, 465, 620, 690, 713, 930, 1380, 1426, 1860, 2139, 2852, 3565, 4278, 7130, 8556, 10695, 14260, 21390, 42780.
What is 42780 in binary?
1010011100011100 (hexadecimal A71C, octal 123434).
What is the square root of 42780?
About 206.8333, exactly 2√10695.
Is 42780 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 42780?
42780 is a happy number: repeatedly adding the squares of its digits reaches 1.