The number 18420
18420 is a composite number with 24 divisors. Its prime factorisation is × 3 × 5 × 307. Divisors (24): 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60, 307, 614, 921, 1228 … 18420.
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How to work it out
- 1
What is special about 18420: a Harshad number: divisible by its digit sum 15.
- 2
18420 is composite. Its prime factorisation is
- 3
The divisors add up to 51744; without 18420 itself that is 33324, so 18420 is abundant (33324 is more than 18420). Euler's totient φ(18420) = 4896 numbers up to 18420 share no factor with it.
- 4
The digits of 18420 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 61 steps to reach 1.
LaTeX source of the formulas on this page
\[ 18420 = 2^{2} \times 3 \times 5 \times 307 \]18420 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 51744 |
| Euler totient φ(n) | 4896 |
| Square | 339296400 |
| Cube | 6249839688000 |
| Square root | 135.720301 (= 2√4605) |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 61 |
| Scientific notation | 1.842 × |
18420 in other forms
| Form | Value |
|---|---|
| In words | eighteen thousand four hundred and twenty |
| Binary (base 2) | 100011111110100 |
| Octal (base 8) | 43764 |
| Hexadecimal (base 16) | 47F4 |
| Base 3 | 221021020 |
| As time | 18420 seconds = 5 h 7 min 0 s |
Is 18420 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (18420 ÷ 2 = 9210) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (18420 ÷ 3 = 6140) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (18420 ÷ 4 = 4605) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (18420 ÷ 5 = 3684) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (18420 ÷ 6 = 3070) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (18420 ÷ 10 = 1842) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (18420 ÷ 12 = 1535) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 18420 a prime number?
No. 18420 = × 3 × 5 × 307, so it is divisible by 2.
What are the factors of 18420?
1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60, 307, 614, 921, 1228, 1535, 1842, 3070, 3684, 4605, 6140, 9210, 18420.
What is 18420 in binary?
100011111110100 (hexadecimal 47F4, octal 43764).
What is the square root of 18420?
About 135.7203, exactly 2√4605.
Is 18420 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 18420?
18420 is a Harshad number: divisible by its digit sum 15.