In the set of integers, it's 2356, but if we're talking about real numbers or rational numbers, there's no such number defined.
It depends which way you're counting. If you're going the regular way, from small numbers toward bigger numbers, then all the whole numbers from 1 to 999,999 come before 1,000,000 .
190
Y = X- 2 one number before x is odd, two numbers before is even
699 comes before and 701 comes after
2598
9998
8408
1052
1052.
It is 4998.
It is 2598.
3610.
18 606 ad 18 608, respectively.
10000
3143
1055