The number 28400
28400 is a composite number with 30 divisors. Its prime factorisation is × × 71. Divisors (30): 1, 2, 4, 5, 8, 10, 16, 20, 25, 40, 50, 71, 80, 100, 142, 200 … 28400.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
28400 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
28400 is composite. Its prime factorisation is
- 3
The divisors add up to 69192; without 28400 itself that is 40792, so 28400 is abundant (40792 is more than 28400). Euler's totient φ(28400) = 11200 numbers up to 28400 share no factor with it.
- 4
The digits of 28400 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 90 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28400 = 2^{4} \times 5^{2} \times 71 \]28400 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 30 |
| Sum of divisors | 69192 |
| Euler totient φ(n) | 11200 |
| Square | 806560000 |
| Cube | 22906304000000 |
| Square root | 168.522995 (= 20√71) |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 90 |
| Scientific notation | 2.84 × |
28400 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand four hundred |
| Binary (base 2) | 110111011110000 |
| Octal (base 8) | 67360 |
| Hexadecimal (base 16) | 6EF0 |
| Base 3 | 1102221212 |
| As time | 28400 seconds = 7 h 53 min 20 s |
Is 28400 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (28400 ÷ 2 = 14200) | 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 (28400 ÷ 4 = 7100) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (28400 ÷ 5 = 5680) | 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 | Yes (28400 ÷ 8 = 3550) | 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 | Yes (28400 ÷ 10 = 2840) | 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 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 28400 a prime number?
No. 28400 = × × 71, so it is divisible by 2.
What are the factors of 28400?
1, 2, 4, 5, 8, 10, 16, 20, 25, 40, 50, 71, 80, 100, 142, 200, 284, 355, 400, 568, 710, 1136, 1420, 1775, 2840, 3550, 5680, 7100, 14200, 28400.
What is 28400 in binary?
110111011110000 (hexadecimal 6EF0, octal 67360).
What is the square root of 28400?
About 168.5230, exactly 20√71.
Is 28400 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 28400?
It is a composite number with 30 divisors.