Constant matching a chi-five expectation

Let $X_1,X_2,…,X_5$ be i.i.d. $N(0,\sigma^2)$ random variables. Suppose $c$ is such that $$\mathbb{E}\left(c\sqrt{\sum_{i=1}^5 X_i^2}\right)=\sigma.$$ Then the value of $c$ is