The number 79840
79840 is a composite number with 24 divisors. Its prime factorisation is × 5 × 499. Divisors (24): 1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 80, 160, 499, 998, 1996, 2495 … 79840.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
79840 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
79840 is composite. Its prime factorisation is
- 3
The divisors add up to 189000; without 79840 itself that is 109160, so 79840 is abundant (109160 is more than 79840). Euler's totient φ(79840) = 31872 numbers up to 79840 share no factor with it.
- 4
The digits of 79840 add up to 28, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 76 steps to reach 1.
LaTeX source of the formulas on this page
\[ 79840 = 2^{5} \times 5 \times 499 \]79840 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 189000 |
| Euler totient φ(n) | 31872 |
| Square | 6374425600 |
| Cube | 508934139904000 |
| Square root | 282.559728 (= 4√4990) |
| Digit sum / digital root | 28 / 1 |
| Collatz steps to 1 | 76 |
| Scientific notation | 7.984 × |
79840 in other forms
| Form | Value |
|---|---|
| In words | seventy-nine thousand eight hundred and forty |
| Binary (base 2) | 10011011111100000 |
| Octal (base 8) | 233740 |
| Hexadecimal (base 16) | 137E0 |
| Base 3 | 11001112001 |
| As time | 79840 seconds = 22 h 10 min 40 s |
Is 79840 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (79840 ÷ 2 = 39920) | 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 | Yes (79840 ÷ 4 = 19960) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (79840 ÷ 5 = 15968) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 5) | 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 (79840 ÷ 8 = 9980) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (79840 ÷ 10 = 7984) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 79840 a prime number?
No. 79840 = × 5 × 499, so it is divisible by 2.
What are the factors of 79840?
1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 80, 160, 499, 998, 1996, 2495, 3992, 4990, 7984, 9980, 15968, 19960, 39920, 79840.
What is 79840 in binary?
10011011111100000 (hexadecimal 137E0, octal 233740).
What is the square root of 79840?
About 282.5597, exactly 4√4990.
Is 79840 divisible by 3?
No. Its digits add up to 28, which is not a multiple of 3.
What is special about the number 79840?
It is a composite number with 24 divisors.