The number 78813
78813 is a composite number with 20 divisors. Its prime factorisation is × 7 × 139. Divisors (20): 1, 3, 7, 9, 21, 27, 63, 81, 139, 189, 417, 567, 973, 1251, 2919, 3753 … 78813.
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How to work it out
- 1
What is special about 78813: a Harshad number: divisible by its digit sum 27.
- 2
78813 is composite. Its prime factorisation is
- 3
The divisors add up to 135520; without 78813 itself that is 56707, so 78813 is deficient (56707 is less than 78813). Euler's totient φ(78813) = 44712 numbers up to 78813 share no factor with it.
- 4
The digits of 78813 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 76 steps to reach 1.
LaTeX source of the formulas on this page
\[ 78813 = 3^{4} \times 7 \times 139 \]78813 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 135520 |
| Euler totient φ(n) | 44712 |
| Square | 6211488969 |
| Cube | 489546080113797 |
| Square root | 280.736531 (= 9√973) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 76 |
| Scientific notation | 7.8813 × |
78813 in other forms
| Form | Value |
|---|---|
| In words | seventy-eight thousand eight hundred and thirteen |
| Binary (base 2) | 10011001111011101 |
| Octal (base 8) | 231735 |
| Hexadecimal (base 16) | 133DD |
| Base 3 | 11000010000 |
| As time | 78813 seconds = 21 h 53 min 33 s |
Is 78813 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 (78813 ÷ 3 = 26271) | 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 | No (remainder 3) | 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 | Yes (78813 ÷ 7 = 11259) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (78813 ÷ 9 = 8757) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 3) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | 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 78813 a prime number?
No. 78813 = × 7 × 139, so it is divisible by 3.
What are the factors of 78813?
1, 3, 7, 9, 21, 27, 63, 81, 139, 189, 417, 567, 973, 1251, 2919, 3753, 8757, 11259, 26271, 78813.
What is 78813 in binary?
10011001111011101 (hexadecimal 133DD, octal 231735).
What is the square root of 78813?
About 280.7365, exactly 9√973.
Is 78813 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 78813?
78813 is a Harshad number: divisible by its digit sum 27.