The sum of the individual bit values gives the number required to set that combination of bits.

Bit 0 has the value of 2 to the power of zero; ie, 1
Bit 1 has the value of 2 to the power of one; ie, 2
Bit 2 has the value of 2 to the power of two; ie, 4
:
Bit 14 has the value of 2 to the power of fourteen; ie, 16384

So, to set bits 0, 2, and 14, the value is 1 + 4 +16284 = 16289.