The number 33991
33991 is a composite number with 4 divisors. Its prime factorisation is 19 × 1789. Divisors (4): 1, 19, 1789, 33991.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 33991: a semiprime: 19 × 1789, the product of two primes.
- 2
33991 is composite. Its prime factorisation is
- 3
The divisors add up to 35800; without 33991 itself that is 1809, so 33991 is deficient (1809 is less than 33991). Euler's totient φ(33991) = 32184 numbers up to 33991 share no factor with it.
- 4
The digits of 33991 add up to 25, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 85 steps to reach 1.
LaTeX source of the formulas on this page
\[ 33991 = 19 \times 1789 \]
33991 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 35800 |
| Euler totient φ(n) | 32184 |
| Square | 1155388081 |
| Cube | 39272796261271 |
| Square root | 184.366483 |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 85 |
| Scientific notation | 3.3991 × |
33991 in other forms
| Form | Value |
|---|---|
| In words | thirty-three thousand nine hundred and ninety-one |
| Binary (base 2) | 1000010011000111 |
| Octal (base 8) | 102307 |
| Hexadecimal (base 16) | 84C7 |
| Base 3 | 1201121221 |
| As time | 33991 seconds = 9 h 26 min 31 s |
Is 33991 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 3) | 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 6) | 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 7) | 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 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 33991 a prime number?
No. 33991 = 19 × 1789, so it is divisible by 19.
What are the factors of 33991?
1, 19, 1789, 33991.
What is 33991 in binary?
1000010011000111 (hexadecimal 84C7, octal 102307).
What is the square root of 33991?
About 184.3665.
Is 33991 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 33991?
33991 is a semiprime: 19 × 1789, the product of two primes.