A new theorem on the prime-counting function

For $x>0$ let $\pi (x)$ denote the number of primes not exceeding $x$. For integers $a$ and $m>0$, we determine when there is an integer $n>1$ with $\pi (n)=(n+a)\mathrm{/}m$. In particular, we show that for any integers $m>2$ and $a\le \lceil e^{m-1}\mathrm{/}(m-1)\rceil$ there is an integer $n>1$ with $\pi (n)=(n+a)\mathrm{/}m$. Consequently, for any integer $m>4$ there is a positive integer $n$ with $\pi (mn)=m+n$. We also pose several conjectures for further research; for example, we conjecture that for each $m=1,2,3,\dots$ there is a positive integer $n$ such that $m+n$ divides $p_m+p_n$, where $p_k$ denotes the $k$-th prime.