The number 15420
15420 is a composite number with 24 divisors. Its prime factorisation is × 3 × 5 × 257. Divisors (24): 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60, 257, 514, 771, 1028 … 15420.
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How to work it out
- 1
What is special about 15420: a Harshad number: divisible by its digit sum 12.
- 2
15420 is composite. Its prime factorisation is
- 3
The divisors add up to 43344; without 15420 itself that is 27924, so 15420 is abundant (27924 is more than 15420). Euler's totient φ(15420) = 4096 numbers up to 15420 share no factor with it.
- 4
The digits of 15420 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 53 steps to reach 1.
LaTeX source of the formulas on this page
\[ 15420 = 2^{2} \times 3 \times 5 \times 257 \]15420 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 43344 |
| Euler totient φ(n) | 4096 |
| Square | 237776400 |
| Cube | 3666512088000 |
| Square root | 124.177293 (= 2√3855) |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 53 |
| Scientific notation | 1.542 × |
15420 in other forms
| Form | Value |
|---|---|
| In words | fifteen thousand four hundred and twenty |
| Binary (base 2) | 11110000111100 |
| Octal (base 8) | 36074 |
| Hexadecimal (base 16) | 3C3C |
| Base 3 | 210011010 |
| As time | 15420 seconds = 4 h 17 min 0 s |
Is 15420 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (15420 ÷ 2 = 7710) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (15420 ÷ 3 = 5140) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (15420 ÷ 4 = 3855) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (15420 ÷ 5 = 3084) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (15420 ÷ 6 = 2570) | 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 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 (15420 ÷ 10 = 1542) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (15420 ÷ 12 = 1285) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 15420 a prime number?
No. 15420 = × 3 × 5 × 257, so it is divisible by 2.
What are the factors of 15420?
1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60, 257, 514, 771, 1028, 1285, 1542, 2570, 3084, 3855, 5140, 7710, 15420.
What is 15420 in binary?
11110000111100 (hexadecimal 3C3C, octal 36074).
What is the square root of 15420?
About 124.1773, exactly 2√3855.
Is 15420 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 15420?
15420 is a Harshad number: divisible by its digit sum 12.