Question 174696
What a strange statement. All numbers are different.
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But, 2 is the only even prime number, and is the smallest prime number (1 is not considered).
7 is a prime number.
77 is the product of 2 prime numbers.
84 is an even number, and is compound (not prime), as all even numbers except 2 are. 
84 has a factor of 7, as does 7 and 77. 84 is the sum of the 2 numbers preceding it, too.