The number 1 is not a prime number Why?
First: What is the prime number: It is that which can be divided by 1 and by itself
Example: {........, 2,3,5,7,11}
So it looks like the number 1 should be a prime number, right?
Because it applies the definition of a prime number?
In the past, it was considered a prime number, but after the advance of science, mathematicians had to exclude it from the primes.
Why?
Eliminate for good reason, there's an important theory in mathematics called
"The Fundamental Theorem of arithmetic"
It says that any positive integer must be a prime number or it can be written as a unique and distinct form of multiplying primes.
Not understood? Bringing an example would be a good solution
15 is a positive integer, not a prime
So 15 = 3 * 5
But there is an important word in the theory "distinct."
But
15 = 3 * 5
15 = 3 * 5 * 1
15 = 3 * 5 * 1 * 1
Here is the problem! If 1 were a prime number, we wouldn't have a unique way of writing it as a multiplication of primes.
So they had to exclude 1 out of the theory
It became a number of primes except for 1.
This is a reason to exclude 1 from the prime numbers.
So 1 is not a prime or complex number