The number 78421
78421 is a composite number with 8 divisors. Its prime factorisation is 7 × 17 × 659. Divisors (8): 1, 7, 17, 119, 659, 4613, 11203, 78421.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
78421 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
78421 is composite. Its prime factorisation is
- 3
The divisors add up to 95040; without 78421 itself that is 16619, so 78421 is deficient (16619 is less than 78421). Euler's totient φ(78421) = 63168 numbers up to 78421 share no factor with it.
- 4
The digits of 78421 add up to 22, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 138 steps to reach 1.
LaTeX source of the formulas on this page
\[ 78421 = 7 \times 17 \times 659 \]
78421 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 95040 |
| Euler totient φ(n) | 63168 |
| Square | 6149853241 |
| Cube | 482277641012461 |
| Square root | 280.037497 |
| Digit sum / digital root | 22 / 4 |
| Collatz steps to 1 | 138 |
| Scientific notation | 7.8421 × |
78421 in other forms
| Form | Value |
|---|---|
| In words | seventy-eight thousand four hundred and twenty-one |
| Binary (base 2) | 10011001001010101 |
| Octal (base 8) | 231125 |
| Hexadecimal (base 16) | 13255 |
| Base 3 | 10222120111 |
| As time | 78421 seconds = 21 h 47 min 1 s |
Is 78421 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 | No (remainder 1) | 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 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (78421 ÷ 7 = 11203) | 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 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 78421 a prime number?
No. 78421 = 7 × 17 × 659, so it is divisible by 7.
What are the factors of 78421?
1, 7, 17, 119, 659, 4613, 11203, 78421.
What is 78421 in binary?
10011001001010101 (hexadecimal 13255, octal 231125).
What is the square root of 78421?
About 280.0375.
Is 78421 divisible by 3?
No. Its digits add up to 22, which is not a multiple of 3.
What is special about the number 78421?
It is a composite number with 8 divisors.