Which of the following is NOT one of the first several prime numbers?

The question asks for a number that is not among the first several prime numbers. A prime number is defined as a natural number greater than 1 that has no positive divisors other than 1 and itself.

The number 15 is not a prime number because it can be divided evenly by 1, 3, 5, and 15. Specifically, 15 can be factored into 3 and 5 (3 × 5 = 15), indicating that it has divisors other than 1 and itself.

In contrast, 11, 19, and 7 are all prime numbers. Each of these numbers can only be divided evenly by 1 and itself. Thus, identifying 15 as the number that does not belong among the first several prime numbers is correct based on the fundamental definition of prime numbers.