The number 3721
3721 is a perfect square (61²). Its prime factorisation is . Divisors (3): 1, 61, 3721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 3721: a perfect square (61²); the square of a prime (61²).
- 2
3721 is composite. Its prime factorisation is
- 3
The divisors add up to 3783; without 3721 itself that is 62, so 3721 is deficient (62 is less than 3721). Euler's totient φ(3721) = 3660 numbers up to 3721 share no factor with it.
- 4
The digits of 3721 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 69 steps to reach 1.
LaTeX source of the formulas on this page
\[ 3721 = 61^{2} \]3721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 3 |
| Sum of divisors | 3783 |
| Euler totient φ(n) | 3660 |
| Square | 13845841 |
| Cube | 51520374361 |
| Square root | 61 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 69 |
| Scientific notation | 3.721 × |
| Perfect power |
3721 in other forms
| Form | Value |
|---|---|
| In words | three thousand seven hundred and twenty-one |
| Roman numerals | MMMDCCXXI |
| Binary (base 2) | 111010001001 |
| Octal (base 8) | 7211 |
| Hexadecimal (base 16) | E89 |
| Base 3 | 12002211 |
| As time | 3721 seconds = 1 h 2 min 1 s |
Is 3721 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 | No (remainder 4) | 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 4) | 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 3) | 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 3721 a prime number?
No. 3721 = , so it is divisible by 61.
What are the factors of 3721?
1, 61, 3721.
What is 3721 in binary?
111010001001 (hexadecimal E89, octal 7211).
What is the square root of 3721?
61, because 61 × 61 = 3721.
What is 3721 in Roman numerals?
MMMDCCXXI.
Is 3721 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 3721?
3721 is a perfect square (61²); the square of a prime (61²).