The number 72981
72981 is a composite number with 20 divisors. Its prime factorisation is × 17 × 53. Divisors (20): 1, 3, 9, 17, 27, 51, 53, 81, 153, 159, 459, 477, 901, 1377, 1431, 2703 … 72981.
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How to work it out
- 1
What is special about 72981: a Harshad number: divisible by its digit sum 27.
- 2
72981 is composite. Its prime factorisation is
- 3
The divisors add up to 117612; without 72981 itself that is 44631, so 72981 is deficient (44631 is less than 72981). Euler's totient φ(72981) = 44928 numbers up to 72981 share no factor with it.
- 4
The digits of 72981 add up to 27, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 63 steps to reach 1.
LaTeX source of the formulas on this page
\[ 72981 = 3^{4} \times 17 \times 53 \]72981 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 117612 |
| Euler totient φ(n) | 44928 |
| Square | 5326226361 |
| Cube | 388713326052141 |
| Square root | 270.149958 (= 9√901) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 63 |
| Scientific notation | 7.2981 × |
72981 in other forms
| Form | Value |
|---|---|
| In words | seventy-two thousand nine hundred and eighty-one |
| Binary (base 2) | 10001110100010101 |
| Octal (base 8) | 216425 |
| Hexadecimal (base 16) | 11D15 |
| Base 3 | 10201010000 |
| As time | 72981 seconds = 20 h 16 min 21 s |
Is 72981 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 (72981 ÷ 3 = 24327) | 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 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (72981 ÷ 9 = 8109) | 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 72981 a prime number?
No. 72981 = × 17 × 53, so it is divisible by 3.
What are the factors of 72981?
1, 3, 9, 17, 27, 51, 53, 81, 153, 159, 459, 477, 901, 1377, 1431, 2703, 4293, 8109, 24327, 72981.
What is 72981 in binary?
10001110100010101 (hexadecimal 11D15, octal 216425).
What is the square root of 72981?
About 270.1500, exactly 9√901.
Is 72981 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 72981?
72981 is a Harshad number: divisible by its digit sum 27.