The number 2356 in base 10 can be written $2\times {10}^3+3\times {10}^2+5\times {10}^1+6\times {10}^0=2000+300+50+6$ "

So the number 234561 in base y can be written $2\times y^5+3\times y^4+4\times y^3+5\times y^2+6\times y^1+1\times y^0$

How about factorising?