Lcm Gcd

Let $\overline{739ABC}$ be a 6-digit number that is divisible by 7, 8 and 9. Denote $M$ and $N$ as two possible lowest common multiple of the three integers, $A,B$ and $C$ , such that $P = \gcd(M,N)$ . Find $\sqrt{\dfrac{M+N}{P^{2/3} } } .$

If you think that it is impossible to have two lowest common multiples, submit your answer as 3.142.