The number 42105
42105 is a composite number with 16 divisors. Its prime factorisation is 3 × 5 × 7 × 401. Divisors (16): 1, 3, 5, 7, 15, 21, 35, 105, 401, 1203, 2005, 2807, 6015, 8421, 14035, 42105.
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How to work it out
- 1
42105 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
42105 is composite. Its prime factorisation is
- 3
The divisors add up to 77184; without 42105 itself that is 35079, so 42105 is deficient (35079 is less than 42105). Euler's totient φ(42105) = 19200 numbers up to 42105 share no factor with it.
- 4
The digits of 42105 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 119 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42105 = 3 \times 5 \times 7 \times 401 \]
42105 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 77184 |
| Euler totient φ(n) | 19200 |
| Square | 1772831025 |
| Cube | 74645050307625 |
| Square root | 205.195029 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 119 |
| Scientific notation | 4.2105 × |
42105 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand one hundred and five |
| Binary (base 2) | 1010010001111001 |
| Octal (base 8) | 122171 |
| Hexadecimal (base 16) | A479 |
| Base 3 | 2010202110 |
| As time | 42105 seconds = 11 h 41 min 45 s |
Is 42105 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 (42105 ÷ 3 = 14035) | 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 | Yes (42105 ÷ 5 = 8421) | 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 | Yes (42105 ÷ 7 = 6015) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | 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 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 42105 a prime number?
No. 42105 = 3 × 5 × 7 × 401, so it is divisible by 3.
What are the factors of 42105?
1, 3, 5, 7, 15, 21, 35, 105, 401, 1203, 2005, 2807, 6015, 8421, 14035, 42105.
What is 42105 in binary?
1010010001111001 (hexadecimal A479, octal 122171).
What is the square root of 42105?
About 205.1950.
Is 42105 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 42105?
It is a composite number with 16 divisors.