The number 278
278 is a composite number with 4 divisors. Its prime factorisation is 2 × 139. Divisors (4): 1, 2, 139, 278.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 278: a semiprime: 2 × 139, the product of two primes.
- 2
278 is composite. Its prime factorisation is
- 3
The divisors add up to 420; without 278 itself that is 142, so 278 is deficient (142 is less than 278). Euler's totient φ(278) = 138 numbers up to 278 share no factor with it.
- 4
The digits of 278 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 42 steps to reach 1.
LaTeX source of the formulas on this page
\[ 278 = 2 \times 139 \]
278 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 420 |
| Euler totient φ(n) | 138 |
| Square | 77284 |
| Cube | 21484952 |
| Square root | 16.673332 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 42 |
| Scientific notation | 2.78 × |
278 in other forms
| Form | Value |
|---|---|
| In words | two hundred and seventy-eight |
| Roman numerals | CCLXXVIII |
| Binary (base 2) | 100010110 |
| Octal (base 8) | 426 |
| Hexadecimal (base 16) | 116 |
| Base 3 | 101022 |
| As time | 278 seconds = 4 min 38 s |
Is 278 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (278 ÷ 2 = 139) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 2) | 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 3) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 | No (remainder 8) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 2) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 278 a prime number?
No. 278 = 2 × 139, so it is divisible by 2.
What are the factors of 278?
1, 2, 139, 278.
What is 278 in binary?
100010110 (hexadecimal 116, octal 426).
What is the square root of 278?
About 16.6733.
What is 278 in Roman numerals?
CCLXXVIII.
Is 278 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 278?
278 is a semiprime: 2 × 139, the product of two primes.