In this paper, we studied the influence of centralizers on the structure of groups, and demonstrated that Janko simple groups can be uniquely determined by two crucial quantitative properties: its even-order components of the group and the set ${\pi }_{p_m}(G)$. Here, $G$ represents a finite group, $\pi (G)$ is the set of prime factors of the order of $G$, $p_m$ is the largest element in $\pi (G)$, and ${\pi }_{p_m}(G)=\{|C_G(x)||x\in G$ and $|x|=p_m\}$ denotes the set of orders of centralizers of $p_m$-order elements in $G$.