IMO 1976 LL GDR18

Prove that the number 191976 + 761976:

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IMO 1976 LL GDR18

Origin: GDR

Problem

Prove that the number 191976 + 761976: (a) is divisible by the (Fermat) prime number F4 = 224 + 1; (b) is divisible by at least four distinct primes other than F4.