25017

i am not really sure but as if you take in persective that if it was monday today and that in 7 days it will be monday again, then in 14 days, than 21 and so on.
as this goes in the 7 times table, any nuber not divisible by 7 will not be a monday. however, it matters how many remanders there are.
e.g.from monday, in 29 days what day will it be?:
29/7=4 r1
which equals to monday + one day= tuesday