The number of pandigital number

In mathematics, a pandigital number is an integer that in a given base B has each digit {0,1,2,3,...,B-1} at least once.

Given two positive integers B and L, let $C(B,L)$ be the number of all the L-digit pandigital numbers in base B. For example, $C(3,3)=4$, there are only four 3-digit pandigital numbers in base 3, namely $(102{)}_3$, $(120{)}_3$, $(201{)}_3$, and $(210{)}_3$

Now we define a new function $D(B,N)={\displaystyle \sum _{L=1}^{N}C(B,L)}$

You are given $D(5,10)=4865472$ and $D(123,321)mod1000000007=844902472$

Find $D(12345678,87654321)mod1000000007$

Note: leading zeroes are not allowed.