The number 39981
39981 is a composite number with 4 divisors. Its prime factorisation is 3 × 13327. Divisors (4): 1, 3, 13327, 39981.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 39981: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 3 × 13327, the product of two primes.
- 2
39981 is composite. Its prime factorisation is
- 3
The divisors add up to 53312; without 39981 itself that is 13331, so 39981 is deficient (13331 is less than 39981). Euler's totient φ(39981) = 26652 numbers up to 39981 share no factor with it.
- 4
The digits of 39981 add up to 30, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 67 steps to reach 1.
LaTeX source of the formulas on this page
\[ 39981 = 3 \times 13327 \]
39981 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 53312 |
| Euler totient φ(n) | 26652 |
| Square | 1598480361 |
| Cube | 63908843313141 |
| Square root | 199.952494 |
| Digit sum / digital root | 30 / 3 |
| Collatz steps to 1 | 67 |
| Scientific notation | 3.9981 × |
39981 in other forms
| Form | Value |
|---|---|
| In words | thirty-nine thousand nine hundred and eighty-one |
| Binary (base 2) | 1001110000101101 |
| Octal (base 8) | 116055 |
| Hexadecimal (base 16) | 9C2D |
| Base 3 | 2000211210 |
| As time | 39981 seconds = 11 h 6 min 21 s |
Is 39981 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 (39981 ÷ 3 = 13327) | 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 3) | 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 5) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | 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 39981 a prime number?
No. 39981 = 3 × 13327, so it is divisible by 3.
What are the factors of 39981?
1, 3, 13327, 39981.
What is 39981 in binary?
1001110000101101 (hexadecimal 9C2D, octal 116055).
What is the square root of 39981?
About 199.9525.
Is 39981 divisible by 3?
Yes. Its digits add up to 30, a multiple of 3.
What is special about the number 39981?
39981 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 3 × 13327, the product of two primes.