Playing With Numbers

If n = 10800,
(a) Find total number of divisor of n.
(b) The number of even divisor.
(c) Find the number of divisor of the form 4m + 2.
(d) Find the number of divisor which are multiple of 15.
In the formula, $$f=\frac{C}{L}$$, if $$C = 3 \times 10^{10}$$ and $$L = 6 \times 10^{-5},\, f =$$
The least number which when divided by $$5, 6, 7$$ and $$8$$ leaves a remainder $$3$$ is