28

This number is a composite.

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28 is a perfect number expressible as the sum of first five nonprime numbers, i.e., 1 + 4 + 6 + 8 + 9 = 28. [Gaydos]

There are 28 prime numbers with distinct digits that are each the sum of the first n primes. The largest is 906437281 which is the sum of the first 13306 primes. [Gaydos]