What type of numbers can only be divided by themselves and 1?

The characteristic that defines a number that can only be divided by itself and 1 is known as a prime number. A prime number is any natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers. This means that the only divisors of a prime number are 1 and the number itself.

For example, the number 5 is prime because its only divisors are 1 and 5. In contrast, composite numbers have additional divisors. For example, the number 4 can be divided by 1, 2, and 4, making it composite. Natural numbers include all positive integers, starting from 1, but this range includes both prime and composite numbers. Whole numbers are similar but also include zero.

Therefore, the correct classification for numbers that can only be divided by themselves and 1 is prime numbers, as they meet the specific criteria while the other types include a broader spectrum of numbers, including those that can be divided by more than just themselves and 1.