The number 42840
42840 is a composite number with 96 divisors. Its prime factorisation is × × 5 × 7 × 17. Divisors (96): 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 17, 18, 20 … 42840.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 42840: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 18.
- 2
42840 is composite. Its prime factorisation is
- 3
The divisors add up to 168480; without 42840 itself that is 125640, so 42840 is abundant (125640 is more than 42840). Euler's totient φ(42840) = 9216 numbers up to 42840 share no factor with it.
- 4
The digits of 42840 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 101 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42840 = 2^{3} \times 3^{2} \times 5 \times 7 \times 17 \]42840 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 96 |
| Sum of divisors | 168480 |
| Euler totient φ(n) | 9216 |
| Square | 1835265600 |
| Cube | 78622778304000 |
| Square root | 206.978260 (= 6√1190) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 101 |
| Scientific notation | 4.284 × |
42840 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand eight hundred and forty |
| Binary (base 2) | 1010011101011000 |
| Octal (base 8) | 123530 |
| Hexadecimal (base 16) | A758 |
| Base 3 | 2011202200 |
| As time | 42840 seconds = 11 h 54 min 0 s |
Is 42840 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (42840 ÷ 2 = 21420) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (42840 ÷ 3 = 14280) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (42840 ÷ 4 = 10710) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (42840 ÷ 5 = 8568) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (42840 ÷ 6 = 7140) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (42840 ÷ 7 = 6120) | 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 | Yes (42840 ÷ 8 = 5355) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (42840 ÷ 9 = 4760) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (42840 ÷ 10 = 4284) | 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 | Yes (42840 ÷ 12 = 3570) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 42840 a prime number?
No. 42840 = × × 5 × 7 × 17, so it is divisible by 2.
What are the factors of 42840?
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 17, 18, 20, 21, 24, 28, 30, 34, 35, 36, 40, 42, 45, 51, 56, 60, 63, 68, 70, 72, 84, 85, 90, 102, 105, 119, 120, 126, 136, 140, 153, 168, 170, 180, 204, 210, 238, 252, 255, 280, 306, 315, 340, 357, 360, 408, 420, 476, 504, 510, 595, 612, 630, 680, 714, 765, 840, 952, 1020, 1071, 1190, 1224, 1260, 1428, 1530, 1785, 2040, 2142, 2380, 2520, 2856, 3060, 3570, 4284, 4760, 5355, 6120, 7140, 8568, 10710, 14280, 21420, 42840.
What is 42840 in binary?
1010011101011000 (hexadecimal A758, octal 123530).
What is the square root of 42840?
About 206.9783, exactly 6√1190.
Is 42840 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 42840?
42840 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 18.