The number 78390
78390 is a composite number with 48 divisors. Its prime factorisation is 2 × × 5 × 13 × 67. Divisors (48): 1, 2, 3, 5, 6, 9, 10, 13, 15, 18, 26, 30, 39, 45, 65, 67 … 78390.
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How to work it out
- 1
What is special about 78390: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
78390 is composite. Its prime factorisation is
- 3
The divisors add up to 222768; without 78390 itself that is 144378, so 78390 is abundant (144378 is more than 78390). Euler's totient φ(78390) = 19008 numbers up to 78390 share no factor with it.
- 4
The digits of 78390 add up to 27, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 200 steps to reach 1.
LaTeX source of the formulas on this page
\[ 78390 = 2 \times 3^{2} \times 5 \times 13 \times 67 \]78390 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 48 |
| Sum of divisors | 222768 |
| Euler totient φ(n) | 19008 |
| Square | 6144992100 |
| Cube | 481705930719000 |
| Square root | 279.982142 (= 3√8710) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 200 |
| Scientific notation | 7.839 × |
78390 in other forms
| Form | Value |
|---|---|
| In words | seventy-eight thousand three hundred and ninety |
| Binary (base 2) | 10011001000110110 |
| Octal (base 8) | 231066 |
| Hexadecimal (base 16) | 13236 |
| Base 3 | 10222112100 |
| As time | 78390 seconds = 21 h 46 min 30 s |
Is 78390 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (78390 ÷ 2 = 39195) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (78390 ÷ 3 = 26130) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (78390 ÷ 5 = 15678) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (78390 ÷ 6 = 13065) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (78390 ÷ 9 = 8710) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (78390 ÷ 10 = 7839) | 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 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 78390 a prime number?
No. 78390 = 2 × × 5 × 13 × 67, so it is divisible by 2.
What are the factors of 78390?
1, 2, 3, 5, 6, 9, 10, 13, 15, 18, 26, 30, 39, 45, 65, 67, 78, 90, 117, 130, 134, 195, 201, 234, 335, 390, 402, 585, 603, 670, 871, 1005, 1170, 1206, 1742, 2010, 2613, 3015, 4355, 5226, 6030, 7839, 8710, 13065, 15678, 26130, 39195, 78390.
What is 78390 in binary?
10011001000110110 (hexadecimal 13236, octal 231066).
What is the square root of 78390?
About 279.9821, exactly 3√8710.
Is 78390 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 78390?
78390 is a happy number: repeatedly adding the squares of its digits reaches 1.