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Computational investigation of Lehmer’s totient problem. (English) Zbl 1240.11005
Summary: Let $$N$$ be a composite number for which $$k\cdot\varphi(N) = N-1$$. We show that if $$3\mid N$$ then $$\omega (N)\geq 40\,000\,000$$ and $$N > 10^{360\,000\,000}$$.

MSC:
 11A25 Arithmetic functions; related numbers; inversion formulas
Keywords:
Lehmer’s totient problem