The number 3661
3661 is a composite number with 4 divisors. Its prime factorisation is 7 × 523. Divisors (4): 1, 7, 523, 3661.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 3661: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 7 × 523, the product of two primes.
- 2
3661 is composite. Its prime factorisation is
- 3
The divisors add up to 4192; without 3661 itself that is 531, so 3661 is deficient (531 is less than 3661). Euler's totient φ(3661) = 3132 numbers up to 3661 share no factor with it.
- 4
The digits of 3661 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 131 steps to reach 1.
LaTeX source of the formulas on this page
\[ 3661 = 7 \times 523 \]
3661 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 4192 |
| Euler totient φ(n) | 3132 |
| Square | 13402921 |
| Cube | 49068093781 |
| Square root | 60.506198 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 131 |
| Scientific notation | 3.661 × |
3661 in other forms
| Form | Value |
|---|---|
| In words | three thousand six hundred and sixty-one |
| Roman numerals | MMMDCLXI |
| Binary (base 2) | 111001001101 |
| Octal (base 8) | 7115 |
| Hexadecimal (base 16) | E4D |
| Base 3 | 12000121 |
| As time | 3661 seconds = 1 h 1 min 1 s |
Is 3661 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 | No (remainder 1) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (3661 ÷ 7 = 523) | 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 | No (remainder 7) | 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 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 3661 a prime number?
No. 3661 = 7 × 523, so it is divisible by 7.
What are the factors of 3661?
1, 7, 523, 3661.
What is 3661 in binary?
111001001101 (hexadecimal E4D, octal 7115).
What is the square root of 3661?
About 60.5062.
What is 3661 in Roman numerals?
MMMDCLXI.
Is 3661 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 3661?
3661 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 7 × 523, the product of two primes.