The number 428
428 is a composite number with 6 divisors. Its prime factorisation is × 107. Divisors (6): 1, 2, 4, 107, 214, 428.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
428 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
428 is composite. Its prime factorisation is
- 3
The divisors add up to 756; without 428 itself that is 328, so 428 is deficient (328 is less than 428). Euler's totient φ(428) = 212 numbers up to 428 share no factor with it.
- 4
The digits of 428 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 102 steps to reach 1.
LaTeX source of the formulas on this page
\[ 428 = 2^{2} \times 107 \]428 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 756 |
| Euler totient φ(n) | 212 |
| Square | 183184 |
| Cube | 78402752 |
| Square root | 20.688161 (= 2√107) |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 102 |
| Scientific notation | 4.28 × |
428 in other forms
| Form | Value |
|---|---|
| In words | four hundred and twenty-eight |
| Roman numerals | CDXXVIII |
| Binary (base 2) | 110101100 |
| Octal (base 8) | 654 |
| Hexadecimal (base 16) | 1AC |
| Base 3 | 120212 |
| As time | 428 seconds = 7 min 8 s |
Is 428 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (428 ÷ 2 = 214) | 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 | Yes (428 ÷ 4 = 107) | 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 1) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | 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 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 428 a prime number?
No. 428 = × 107, so it is divisible by 2.
What are the factors of 428?
1, 2, 4, 107, 214, 428.
What is 428 in binary?
110101100 (hexadecimal 1AC, octal 654).
What is the square root of 428?
About 20.6882, exactly 2√107.
What is 428 in Roman numerals?
CDXXVIII.
Is 428 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 428?
It is a composite number with 6 divisors.