The number 78402
78402 is a composite number with 16 divisors. Its prime factorisation is 2 × 3 × 73 × 179. Divisors (16): 1, 2, 3, 6, 73, 146, 179, 219, 358, 438, 537, 1074, 13067, 26134, 39201, 78402.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 78402: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
78402 is composite. Its prime factorisation is
- 3
The divisors add up to 159840; without 78402 itself that is 81438, so 78402 is abundant (81438 is more than 78402). Euler's totient φ(78402) = 25632 numbers up to 78402 share no factor with it.
- 4
The digits of 78402 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 169 steps to reach 1.
LaTeX source of the formulas on this page
\[ 78402 = 2 \times 3 \times 73 \times 179 \]
78402 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 159840 |
| Euler totient φ(n) | 25632 |
| Square | 6146873604 |
| Cube | 481927184300808 |
| Square root | 280.003571 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 169 |
| Scientific notation | 7.8402 × |
78402 in other forms
| Form | Value |
|---|---|
| In words | seventy-eight thousand four hundred and two |
| Binary (base 2) | 10011001001000010 |
| Octal (base 8) | 231102 |
| Hexadecimal (base 16) | 13242 |
| Base 3 | 10222112210 |
| As time | 78402 seconds = 21 h 46 min 42 s |
Is 78402 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (78402 ÷ 2 = 39201) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (78402 ÷ 3 = 26134) | 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 | No (remainder 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (78402 ÷ 6 = 13067) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 2) | 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 | No (remainder 2) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | 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 78402 a prime number?
No. 78402 = 2 × 3 × 73 × 179, so it is divisible by 2.
What are the factors of 78402?
1, 2, 3, 6, 73, 146, 179, 219, 358, 438, 537, 1074, 13067, 26134, 39201, 78402.
What is 78402 in binary?
10011001001000010 (hexadecimal 13242, octal 231102).
What is the square root of 78402?
About 280.0036.
Is 78402 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 78402?
78402 is a happy number: repeatedly adding the squares of its digits reaches 1.