The number 51381
51381 is a composite number with 16 divisors. Its prime factorisation is × 11 × 173. Divisors (16): 1, 3, 9, 11, 27, 33, 99, 173, 297, 519, 1557, 1903, 4671, 5709, 17127, 51381.
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How to work it out
- 1
What is special about 51381: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
51381 is composite. Its prime factorisation is
- 3
The divisors add up to 83520; without 51381 itself that is 32139, so 51381 is deficient (32139 is less than 51381). Euler's totient φ(51381) = 30960 numbers up to 51381 share no factor with it.
- 4
The digits of 51381 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 127 steps to reach 1.
LaTeX source of the formulas on this page
\[ 51381 = 3^{3} \times 11 \times 173 \]51381 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 83520 |
| Euler totient φ(n) | 30960 |
| Square | 2640007161 |
| Cube | 135646207939341 |
| Square root | 226.673774 (= 3√5709) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 127 |
| Scientific notation | 5.1381 × |
51381 in other forms
| Form | Value |
|---|---|
| In words | fifty-one thousand three hundred and eighty-one |
| Binary (base 2) | 1100100010110101 |
| Octal (base 8) | 144265 |
| Hexadecimal (base 16) | C8B5 |
| Base 3 | 2121111000 |
| As time | 51381 seconds = 14 h 16 min 21 s |
Is 51381 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (51381 ÷ 3 = 17127) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | 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 | No (remainder 3) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (51381 ÷ 9 = 5709) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | Yes (51381 ÷ 11 = 4671) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 51381 a prime number?
No. 51381 = × 11 × 173, so it is divisible by 3.
What are the factors of 51381?
1, 3, 9, 11, 27, 33, 99, 173, 297, 519, 1557, 1903, 4671, 5709, 17127, 51381.
What is 51381 in binary?
1100100010110101 (hexadecimal C8B5, octal 144265).
What is the square root of 51381?
About 226.6738, exactly 3√5709.
Is 51381 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 51381?
51381 is a happy number: repeatedly adding the squares of its digits reaches 1.