The number 7218
7218 is a composite number with 12 divisors. Its prime factorisation is 2 × × 401. Divisors (12): 1, 2, 3, 6, 9, 18, 401, 802, 1203, 2406, 3609, 7218.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 7218: a Harshad number: divisible by its digit sum 18.
- 2
7218 is composite. Its prime factorisation is
- 3
The divisors add up to 15678; without 7218 itself that is 8460, so 7218 is abundant (8460 is more than 7218). Euler's totient φ(7218) = 2400 numbers up to 7218 share no factor with it.
- 4
The digits of 7218 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 44 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7218 = 2 \times 3^{2} \times 401 \]7218 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 15678 |
| Euler totient φ(n) | 2400 |
| Square | 52099524 |
| Cube | 376054364232 |
| Square root | 84.958814 (= 3√802) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 44 |
| Scientific notation | 7.218 × |
7218 in other forms
| Form | Value |
|---|---|
| In words | seven thousand two hundred and eighteen |
| Binary (base 2) | 1110000110010 |
| Octal (base 8) | 16062 |
| Hexadecimal (base 16) | 1C32 |
| Base 3 | 100220100 |
| As time | 7218 seconds = 2 h 0 min 18 s |
Is 7218 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (7218 ÷ 2 = 3609) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (7218 ÷ 3 = 2406) | 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 | Yes (7218 ÷ 6 = 1203) | 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 2) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (7218 ÷ 9 = 802) | 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 2) | 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 7218 a prime number?
No. 7218 = 2 × × 401, so it is divisible by 2.
What are the factors of 7218?
1, 2, 3, 6, 9, 18, 401, 802, 1203, 2406, 3609, 7218.
What is 7218 in binary?
1110000110010 (hexadecimal 1C32, octal 16062).
What is the square root of 7218?
About 84.9588, exactly 3√802.
Is 7218 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 7218?
7218 is a Harshad number: divisible by its digit sum 18.