The number 1389
1389 is a composite number with 4 divisors. Its prime factorisation is 3 × 463. Divisors (4): 1, 3, 463, 1389.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1389: a semiprime: 3 × 463, the product of two primes.
- 2
1389 is composite. Its prime factorisation is
- 3
The divisors add up to 1856; without 1389 itself that is 467, so 1389 is deficient (467 is less than 1389). Euler's totient φ(1389) = 924 numbers up to 1389 share no factor with it.
- 4
The digits of 1389 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 127 steps to reach 1.
LaTeX source of the formulas on this page
\[ 1389 = 3 \times 463 \]
1389 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 1856 |
| Euler totient φ(n) | 924 |
| Square | 1929321 |
| Cube | 2679826869 |
| Square root | 37.269290 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 127 |
| Scientific notation | 1.389 × |
1389 in other forms
| Form | Value |
|---|---|
| In words | one thousand three hundred and eighty-nine |
| Roman numerals | MCCCLXXXIX |
| Binary (base 2) | 10101101101 |
| Octal (base 8) | 2555 |
| Hexadecimal (base 16) | 56D |
| Base 3 | 1220110 |
| As time | 1389 seconds = 23 min 9 s |
Is 1389 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (1389 ÷ 3 = 463) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | 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 | No (remainder 5) | 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 | No (remainder 9) | 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 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 1389 a prime number?
No. 1389 = 3 × 463, so it is divisible by 3.
What are the factors of 1389?
1, 3, 463, 1389.
What is 1389 in binary?
10101101101 (hexadecimal 56D, octal 2555).
What is the square root of 1389?
About 37.2693.
What is 1389 in Roman numerals?
MCCCLXXXIX.
Is 1389 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 1389?
1389 is a semiprime: 3 × 463, the product of two primes.