Numbers coprime to $210$

Formula. $\varphi(210)=210(1-1/2)(1-1/3)(1-1/5)(1-1/7)=210\cdot\frac12\cdot\frac23\cdot\frac45\cdot\frac67=48$.

IE verification. Count numbers divisible by at least one of $2,3,5,7$ and subtract from $210$; result is $48$.

Conclusion. $48$ coprime integers.