If N has one digit this is not possible. If N has two digits, say N=ab, then {N}=ba so that N−{N}=9(a−b) which yields a−b=1 so the numbers are
N=10,21,32,43,54,65,76,87,98.
Assume there are numbers N with the above property that have m≥3 digits. Thus, we may write
N=aZb
where a∈{1,2,3,…,9} and b∈{0,1,2,3,…,9} are digits and Z is a positive integer with m−2≥1 digits. We may need to include leading zeros in the presentation of Z. Then, {N}=b{Z}a, where {Z} is obtained by writing the digits of Z from right to left. We now have
9=N−{N}=(10m−1a+10Z+b)−(10m−1b+10{Z}+a)
which yields
9=(10m−1−1)(a−b)+10(Z−{Z}).(6)
Because N≥{N}, we must have a≥b.
If a−b=0 then (6) cannot hold because the right-hand side is a multiple of 10 while the left-hand side is not. If a−b≥2 we again raise a contradiction since N≥a⋅10m−1 and {N}≤(b+1)⋅10m−1 imply
9=N−{N}≥(a−b−1)⋅10m−1≥10m−1≥100.
Hence a−b=1 and from (6) we find 9=10m−1−1+10(Z−{Z}) from which we get
{Z}−Z=10m−2−1.(7)
Clearly, Z=0 does not satisfy (7). If Z>0, (7) implies {Z}>10m−2−1. Recall now that Z and {Z} have at most m−2 digits, fewer than m−2 if Z contains leading digits equal to zero. Hence, Z and {Z} cannot exceed 10m−2−1=999…9, the number that consists of m−2 digits 9. This contradiction shows that when m≥3 there is no solution.
Hence, the only numbers satisfying the condition in the problem are the two-digit numbers listed above.