The number 77840
77840 is a composite number with 40 divisors. Its prime factorisation is × 5 × 7 × 139. Divisors (40): 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 56, 70, 80 … 77840.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
77840 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
77840 is composite. Its prime factorisation is
- 3
The divisors add up to 208320; without 77840 itself that is 130480, so 77840 is abundant (130480 is more than 77840). Euler's totient φ(77840) = 26496 numbers up to 77840 share no factor with it.
- 4
The digits of 77840 add up to 26, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 50 steps to reach 1.
LaTeX source of the formulas on this page
\[ 77840 = 2^{4} \times 5 \times 7 \times 139 \]77840 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 40 |
| Sum of divisors | 208320 |
| Euler totient φ(n) | 26496 |
| Square | 6059065600 |
| Cube | 471637666304000 |
| Square root | 278.998208 (= 4√4865) |
| Digit sum / digital root | 26 / 8 |
| Collatz steps to 1 | 50 |
| Scientific notation | 7.784 × |
77840 in other forms
| Form | Value |
|---|---|
| In words | seventy-seven thousand eight hundred and forty |
| Binary (base 2) | 10011000000010000 |
| Octal (base 8) | 230020 |
| Hexadecimal (base 16) | 13010 |
| Base 3 | 10221202222 |
| As time | 77840 seconds = 21 h 37 min 20 s |
Is 77840 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (77840 ÷ 2 = 38920) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 2) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (77840 ÷ 4 = 19460) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (77840 ÷ 5 = 15568) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (77840 ÷ 7 = 11120) | 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 (77840 ÷ 8 = 9730) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 8) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (77840 ÷ 10 = 7784) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 4) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 77840 a prime number?
No. 77840 = × 5 × 7 × 139, so it is divisible by 2.
What are the factors of 77840?
1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 56, 70, 80, 112, 139, 140, 278, 280, 556, 560, 695, 973, 1112, 1390, 1946, 2224, 2780, 3892, 4865, 5560, 7784, 9730, 11120, 15568, 19460, 38920, 77840.
What is 77840 in binary?
10011000000010000 (hexadecimal 13010, octal 230020).
What is the square root of 77840?
About 278.9982, exactly 4√4865.
Is 77840 divisible by 3?
No. Its digits add up to 26, which is not a multiple of 3.
What is special about the number 77840?
It is a composite number with 40 divisors.