The number 445
445 is a composite number with 4 divisors. Its prime factorisation is 5 × 89. Divisors (4): 1, 5, 89, 445.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 445: a semiprime: 5 × 89, the product of two primes.
- 2
445 is composite. Its prime factorisation is
- 3
The divisors add up to 540; without 445 itself that is 95, so 445 is deficient (95 is less than 445). Euler's totient φ(445) = 352 numbers up to 445 share no factor with it.
- 4
The digits of 445 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 71 steps to reach 1.
LaTeX source of the formulas on this page
\[ 445 = 5 \times 89 \]
445 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 540 |
| Euler totient φ(n) | 352 |
| Square | 198025 |
| Cube | 88121125 |
| Square root | 21.095023 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 71 |
| Scientific notation | 4.45 × |
445 in other forms
| Form | Value |
|---|---|
| In words | four hundred and forty-five |
| Roman numerals | CDXLV |
| Binary (base 2) | 110111101 |
| Octal (base 8) | 675 |
| Hexadecimal (base 16) | 1BD |
| Base 3 | 121111 |
| As time | 445 seconds = 7 min 25 s |
Is 445 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 | No (remainder 1) | 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 | Yes (445 ÷ 5 = 89) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 445 a prime number?
No. 445 = 5 × 89, so it is divisible by 5.
What are the factors of 445?
1, 5, 89, 445.
What is 445 in binary?
110111101 (hexadecimal 1BD, octal 675).
What is the square root of 445?
About 21.0950.
What is 445 in Roman numerals?
CDXLV.
Is 445 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 445?
445 is a semiprime: 5 × 89, the product of two primes.