107

This number is a prime.

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Many Lucas numbers are not prime, but "Lucas" is (chemically) prime if we add the atomic numbers of Lu(tetium), Ca(lcium) and S(ulphur): 71 + 20 + 16 = 107. [Necula]

The sum of atomic numbers of five chemical elements that have their symbols embedded in the second author's last name (H,O,Na,K,Er). [Necula]