The number 39720
39720 is a composite number with 32 divisors. Its prime factorisation is × 3 × 5 × 331. Divisors (32): 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120 … 39720.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
39720 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
39720 is composite. Its prime factorisation is
- 3
The divisors add up to 119520; without 39720 itself that is 79800, so 39720 is abundant (79800 is more than 39720). Euler's totient φ(39720) = 10560 numbers up to 39720 share no factor with it.
- 4
The digits of 39720 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 44 steps to reach 1.
LaTeX source of the formulas on this page
\[ 39720 = 2^{3} \times 3 \times 5 \times 331 \]39720 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 119520 |
| Euler totient φ(n) | 10560 |
| Square | 1577678400 |
| Cube | 62665386048000 |
| Square root | 199.298771 (= 2√9930) |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 44 |
| Scientific notation | 3.972 × |
39720 in other forms
| Form | Value |
|---|---|
| In words | thirty-nine thousand seven hundred and twenty |
| Binary (base 2) | 1001101100101000 |
| Octal (base 8) | 115450 |
| Hexadecimal (base 16) | 9B28 |
| Base 3 | 2000111010 |
| As time | 39720 seconds = 11 h 2 min 0 s |
Is 39720 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (39720 ÷ 2 = 19860) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (39720 ÷ 3 = 13240) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (39720 ÷ 4 = 9930) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (39720 ÷ 5 = 7944) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (39720 ÷ 6 = 6620) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 | Yes (39720 ÷ 8 = 4965) | 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 | Yes (39720 ÷ 10 = 3972) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (39720 ÷ 12 = 3310) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 39720 a prime number?
No. 39720 = × 3 × 5 × 331, so it is divisible by 2.
What are the factors of 39720?
1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120, 331, 662, 993, 1324, 1655, 1986, 2648, 3310, 3972, 4965, 6620, 7944, 9930, 13240, 19860, 39720.
What is 39720 in binary?
1001101100101000 (hexadecimal 9B28, octal 115450).
What is the square root of 39720?
About 199.2988, exactly 2√9930.
Is 39720 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 39720?
It is a composite number with 32 divisors.