The number 18440
18440 is a composite number with 16 divisors. Its prime factorisation is × 5 × 461. Divisors (16): 1, 2, 4, 5, 8, 10, 20, 40, 461, 922, 1844, 2305, 3688, 4610, 9220, 18440.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 18440: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
18440 is composite. Its prime factorisation is
- 3
The divisors add up to 41580; without 18440 itself that is 23140, so 18440 is abundant (23140 is more than 18440). Euler's totient φ(18440) = 7360 numbers up to 18440 share no factor with it.
- 4
The digits of 18440 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 110 steps to reach 1.
LaTeX source of the formulas on this page
\[ 18440 = 2^{3} \times 5 \times 461 \]18440 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 41580 |
| Euler totient φ(n) | 7360 |
| Square | 340033600 |
| Cube | 6270219584000 |
| Square root | 135.793962 (= 2√4610) |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 110 |
| Scientific notation | 1.844 × |
18440 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand four hundred and forty |
| Binary (base 2) | 100100000001000 |
| Octal (base 8) | 44010 |
| Hexadecimal (base 16) | 4808 |
| Base 3 | 221021222 |
| As time | 18440 seconds = 5 h 7 min 20 s |
Is 18440 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (18440 ÷ 2 = 9220) | 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 (18440 ÷ 4 = 4610) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (18440 ÷ 5 = 3688) | 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 2) | 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 (18440 ÷ 8 = 2305) | 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 | Yes (18440 ÷ 10 = 1844) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 4) | 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 18440 a prime number?
No. 18440 = × 5 × 461, so it is divisible by 2.
What are the factors of 18440?
1, 2, 4, 5, 8, 10, 20, 40, 461, 922, 1844, 2305, 3688, 4610, 9220, 18440.
What is 18440 in binary?
100100000001000 (hexadecimal 4808, octal 44010).
What is the square root of 18440?
About 135.7940, exactly 2√4610.
Is 18440 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 18440?
18440 is a happy number: repeatedly adding the squares of its digits reaches 1.