Refers to a natural number greater than 1, and there are no other factors except 1 and itself. A natural number with only two positive factors (1 and itself) is a prime number. Numbers greater than 1 but not prime numbers are called composite numbers. 1 and 0 are neither prime numbers nor composite numbers.

For prime numbers within 1000, they are: 2, 3, 5, 7, 1 1, 13, 17, 19, 23, 29, 3/. 103, 107, 109, 1 3, 127, 13 137,/kloc-

The concept of prime numbers can be extended to the range of integers. Prime numbers and their related numbers (that is, prime numbers multiplied by-1, 1) can be called prime numbers, and they can also be said to be positive prime numbers and negative prime numbers. A broader extension is that the correlation number of prime numbers is also called prime numbers.

The unsolved problems of prime numbers:

Debach conjecture is a famous unsolved problem. This conjecture shows that any even number greater than 2 can be expressed as the sum of two prime numbers. Although this conjecture has been verified to a very large value, a universal proof method has not yet been found.

Another famous unsolved problem is the twin prime conjecture. This conjecture shows that there are infinite pairs of prime numbers with a difference of 2. This conjecture was put forward by Alhas Alhas and has not been proved so far.

Although the study of prime numbers is full of challenges, it has not stopped mathematicians from exploring. In recent years, mathematicians have found some new methods and tools to study prime numbers, such as random screening and elliptic curves. These new methods not only improve the efficiency of calculating prime numbers, but also provide a new perspective for us to understand the properties of prime numbers.

Prime number is a basic concept in mathematics, and its research involves many profound theories and methods. Although we already know some basic properties of prime numbers, there are still many unknown problems waiting for us to explore and answer.