The number 87420
87420 is a composite number with 48 divisors. Its prime factorisation is × 3 × 5 × 31 × 47. Divisors (48): 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 31, 47, 60, 62, 93 … 87420.
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How to work it out
- 1
What is special about 87420: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
87420 is composite. Its prime factorisation is
- 3
The divisors add up to 258048; without 87420 itself that is 170628, so 87420 is abundant (170628 is more than 87420). Euler's totient φ(87420) = 22080 numbers up to 87420 share no factor with it.
- 4
The digits of 87420 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 58 steps to reach 1.
LaTeX source of the formulas on this page
\[ 87420 = 2^{2} \times 3 \times 5 \times 31 \times 47 \]87420 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 48 |
| Sum of divisors | 258048 |
| Euler totient φ(n) | 22080 |
| Square | 7642256400 |
| Cube | 668086054488000 |
| Square root | 295.668734 (= 2√21855) |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 58 |
| Scientific notation | 8.742 × |
87420 in other forms
| Form | Value |
|---|---|
| In words | eighty-seven thousand four hundred and twenty |
| Binary (base 2) | 10101010101111100 |
| Octal (base 8) | 252574 |
| Hexadecimal (base 16) | 1557C |
| Base 3 | 11102220210 |
| As time | 87420 seconds = 24 h 17 min 0 s |
Is 87420 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (87420 ÷ 2 = 43710) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (87420 ÷ 3 = 29140) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (87420 ÷ 4 = 21855) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (87420 ÷ 5 = 17484) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (87420 ÷ 6 = 14570) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | 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 4) | 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 (87420 ÷ 10 = 8742) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (87420 ÷ 12 = 7285) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 87420 a prime number?
No. 87420 = × 3 × 5 × 31 × 47, so it is divisible by 2.
What are the factors of 87420?
1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 31, 47, 60, 62, 93, 94, 124, 141, 155, 186, 188, 235, 282, 310, 372, 465, 470, 564, 620, 705, 930, 940, 1410, 1457, 1860, 2820, 2914, 4371, 5828, 7285, 8742, 14570, 17484, 21855, 29140, 43710, 87420.
What is 87420 in binary?
10101010101111100 (hexadecimal 1557C, octal 252574).
What is the square root of 87420?
About 295.6687, exactly 2√21855.
Is 87420 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 87420?
87420 is a happy number: repeatedly adding the squares of its digits reaches 1.