Can a nine digit number composed of 1, 2, 3, 4, 5, 6, 7, 8 and 9 be prime?

Can a nine digit number composed of 1, 2, 3, 4, 5, 6, 7, 8 and 9 be prime?

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45, 45 is a multiple of 3, so this nine digit number has at least three divisors of 1, 3 and itself, which is a composite number; therefore, the number formed cannot be prime

Three digital cards 123, from which one, two, and three are selected to form 1-digit, 2-digit, and 3-digit numbers respectively. Which of them are prime numbers and which of them are combined numbers?

① There are three possibilities to select any one of the three cards, that is, there are three one digit numbers, i.e. 1, 2 and 3, of which only 2 and 3 are prime numbers; ② there are six two digit numbers from any two of the three cards, but the two digit number is the two digit number of 2 and the two digit number of which the sum of one digit and ten digit number is a multiple of 3, which are not prime numbers; therefore, the two digit prime numbers are only 13 and 23, (3) because 1 + 2 + 3 = 6 and 6 can be divided by 3, the three digits from 1, 2 and 3 in any order are not prime numbers; therefore, the prime numbers that meet the requirements are 2, 3, 13, 23 and 31. A: prime numbers are 2, 3, 13, 23 and 31