The mantissa distribution of the primorial numbers
We show that the sequence of mantissas of the primorial numbers $P_n$, defined as the product of the first $n$ prime numbers, is distributed following Benford's law. This is done by proving that the values of the first Chebyshev function at prime numbers are uniformly distributed modulo 1. We provide a convergence rate estimate. We also briefly treat some other sequences defined in the same way as $P_n$.