In certain code , '15789' is written as 'XTZAL' and '2346' is written 'NPSU'. How is '23549' written in that code?

NPTSL

Respective codes have been assigned to the corresponding letters as follows:

1 = X, 5 = T, 7 = Z, 8 = A, 9 = L

2 = N, 3 = P, 4 = S, 6 = U

So, according to the above codes, code for 23549 will be as follows:

NPTSL