The number 51840
51840 is a composite number with 80 divisors. Its prime factorisation is × × 5. Divisors (80): 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 24, 27 … 51840.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 51840: a Harshad number: divisible by its digit sum 18.
- 2
51840 is composite. Its prime factorisation is
- 3
The divisors add up to 185130; without 51840 itself that is 133290, so 51840 is abundant (133290 is more than 51840). Euler's totient φ(51840) = 13824 numbers up to 51840 share no factor with it.
- 4
The digits of 51840 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 34 steps to reach 1.
LaTeX source of the formulas on this page
\[ 51840 = 2^{7} \times 3^{4} \times 5 \]51840 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 80 |
| Sum of divisors | 185130 |
| Euler totient φ(n) | 13824 |
| Square | 2687385600 |
| Cube | 139314069504000 |
| Square root | 227.683992 (= 72√10) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 34 |
| Scientific notation | 5.184 × |
51840 in other forms
| Form | Value |
|---|---|
| In words | fifty-one thousand eight hundred and forty |
| Binary (base 2) | 1100101010000000 |
| Octal (base 8) | 145200 |
| Hexadecimal (base 16) | CA80 |
| Base 3 | 2122010000 |
| As time | 51840 seconds = 14 h 24 min 0 s |
Is 51840 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (51840 ÷ 2 = 25920) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (51840 ÷ 3 = 17280) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (51840 ÷ 4 = 12960) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (51840 ÷ 5 = 10368) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (51840 ÷ 6 = 8640) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 (51840 ÷ 8 = 6480) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (51840 ÷ 9 = 5760) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (51840 ÷ 10 = 5184) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (51840 ÷ 12 = 4320) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 51840 a prime number?
No. 51840 = × × 5, so it is divisible by 2.
What are the factors of 51840?
1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 24, 27, 30, 32, 36, 40, 45, 48, 54, 60, 64, 72, 80, 81, 90, 96, 108, 120, 128, 135, 144, 160, 162, 180, 192, 216, 240, 270, 288, 320, 324, 360, 384, 405, 432, 480, 540, 576, 640, 648, 720, 810, 864, 960, 1080, 1152, 1296, 1440, 1620, 1728, 1920, 2160, 2592, 2880, 3240, 3456, 4320, 5184, 5760, 6480, 8640, 10368, 12960, 17280, 25920, 51840.
What is 51840 in binary?
1100101010000000 (hexadecimal CA80, octal 145200).
What is the square root of 51840?
About 227.6840, exactly 72√10.
Is 51840 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 51840?
51840 is a Harshad number: divisible by its digit sum 18.