The number 25840
25840 is a composite number with 40 divisors. Its prime factorisation is × 5 × 17 × 19. Divisors (40): 1, 2, 4, 5, 8, 10, 16, 17, 19, 20, 34, 38, 40, 68, 76, 80 … 25840.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 25840: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 19.
- 2
25840 is composite. Its prime factorisation is
- 3
The divisors add up to 66960; without 25840 itself that is 41120, so 25840 is abundant (41120 is more than 25840). Euler's totient φ(25840) = 9216 numbers up to 25840 share no factor with it.
- 4
The digits of 25840 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 77 steps to reach 1.
LaTeX source of the formulas on this page
\[ 25840 = 2^{4} \times 5 \times 17 \times 19 \]25840 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 40 |
| Sum of divisors | 66960 |
| Euler totient φ(n) | 9216 |
| Square | 667705600 |
| Cube | 17253512704000 |
| Square root | 160.748250 (= 4√1615) |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 77 |
| Scientific notation | 2.584 × |
25840 in other forms
| Form | Value |
|---|---|
| In words | twenty-five thousand eight hundred and forty |
| Binary (base 2) | 110010011110000 |
| Octal (base 8) | 62360 |
| Hexadecimal (base 16) | 64F0 |
| Base 3 | 1022110001 |
| As time | 25840 seconds = 7 h 10 min 40 s |
Is 25840 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (25840 ÷ 2 = 12920) | 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 (25840 ÷ 4 = 6460) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (25840 ÷ 5 = 5168) | 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 3) | 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 (25840 ÷ 8 = 3230) | 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 (25840 ÷ 10 = 2584) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | 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 25840 a prime number?
No. 25840 = × 5 × 17 × 19, so it is divisible by 2.
What are the factors of 25840?
1, 2, 4, 5, 8, 10, 16, 17, 19, 20, 34, 38, 40, 68, 76, 80, 85, 95, 136, 152, 170, 190, 272, 304, 323, 340, 380, 646, 680, 760, 1292, 1360, 1520, 1615, 2584, 3230, 5168, 6460, 12920, 25840.
What is 25840 in binary?
110010011110000 (hexadecimal 64F0, octal 62360).
What is the square root of 25840?
About 160.7483, exactly 4√1615.
Is 25840 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 25840?
25840 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 19.