The number 841
841 is a perfect square (29²). Its prime factorisation is . Divisors (3): 1, 29, 841.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 841: a perfect square (29²); the square of a prime (29²).
- 2
841 is composite. Its prime factorisation is
- 3
The divisors add up to 871; without 841 itself that is 30, so 841 is deficient (30 is less than 841). Euler's totient φ(841) = 812 numbers up to 841 share no factor with it.
- 4
The digits of 841 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 41 steps to reach 1.
LaTeX source of the formulas on this page
\[ 841 = 29^{2} \]841 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 3 |
| Sum of divisors | 871 |
| Euler totient φ(n) | 812 |
| Square | 707281 |
| Cube | 594823321 |
| Square root | 29 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 41 |
| Scientific notation | 8.41 × |
| Perfect power |
841 in other forms
| Form | Value |
|---|---|
| In words | eight hundred and forty-one |
| Roman numerals | DCCCXLI |
| Binary (base 2) | 1101001001 |
| Octal (base 8) | 1511 |
| Hexadecimal (base 16) | 349 |
| Base 3 | 1011011 |
| As time | 841 seconds = 14 min 1 s |
Is 841 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 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 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 5) | 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 841 a prime number?
No. 841 = , so it is divisible by 29.
What are the factors of 841?
1, 29, 841.
What is 841 in binary?
1101001001 (hexadecimal 349, octal 1511).
What is the square root of 841?
29, because 29 × 29 = 841.
What is 841 in Roman numerals?
DCCCXLI.
Is 841 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 841?
841 is a perfect square (29²); the square of a prime (29²).