The number 816
816 is a composite number with 20 divisors. Its prime factorisation is × 3 × 17. Divisors (20): 1, 2, 3, 4, 6, 8, 12, 16, 17, 24, 34, 48, 51, 68, 102, 136 … 816.
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How to work it out
- 1
816 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
816 is composite. Its prime factorisation is
- 3
The divisors add up to 2232; without 816 itself that is 1416, so 816 is abundant (1416 is more than 816). Euler's totient φ(816) = 256 numbers up to 816 share no factor with it.
- 4
The digits of 816 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 28 steps to reach 1.
LaTeX source of the formulas on this page
\[ 816 = 2^{4} \times 3 \times 17 \]816 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 2232 |
| Euler totient φ(n) | 256 |
| Square | 665856 |
| Cube | 543338496 |
| Square root | 28.565714 (= 4√51) |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 28 |
| Scientific notation | 8.16 × |
816 in other forms
| Form | Value |
|---|---|
| In words | eight hundred and sixteen |
| Roman numerals | DCCCXVI |
| Binary (base 2) | 1100110000 |
| Octal (base 8) | 1460 |
| Hexadecimal (base 16) | 330 |
| Base 3 | 1010020 |
| As time | 816 seconds = 13 min 36 s |
Is 816 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (816 ÷ 2 = 408) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (816 ÷ 3 = 272) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (816 ÷ 4 = 204) | 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 | Yes (816 ÷ 6 = 136) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 (816 ÷ 8 = 102) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 6) | 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 | Yes (816 ÷ 12 = 68) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 816 a prime number?
No. 816 = × 3 × 17, so it is divisible by 2.
What are the factors of 816?
1, 2, 3, 4, 6, 8, 12, 16, 17, 24, 34, 48, 51, 68, 102, 136, 204, 272, 408, 816.
What is 816 in binary?
1100110000 (hexadecimal 330, octal 1460).
What is the square root of 816?
About 28.5657, exactly 4√51.
What is 816 in Roman numerals?
DCCCXVI.
Is 816 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 816?
It is a composite number with 20 divisors.