In a code language, if FORTUNE is written as 716192122156, then how will OCTOBER be written in the same language?

16421163619

1  2    3    4   5    6   7     8    9  10  11  12  13

 A   B   C    D   E    F   G    H    I    J    K    L   M

 ↓    ↓    ↓    ↓    ↓     ↓   ↓    ↓     ↓   ↓    ↓    ↓    ↓

 Z   Y    X   W   V    U   T    S    R   Q   P    O   N

26  25  24  23  22  21  20  19  18  17  16  15  14

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THE LOGIC FOLLOWED HERE IS :

ADDING 1 TO THE ALPHABET

F (6) → (+1) → 7

O (15) → (+1) → 16

R (18) → (+1) → 19

T (20) → (+1) → 21

U (21) → (+1) → 22

N (14) → (+1) → 15

E (5) → (+1) → 6

SIMILARLY

O (15) → (+1) → 16

C (3) → (+1) → 4

T (20) → (+1) → 21

O (15) → (+1) → 16

B (2) → (+1) → 3

E (5) → (+1) → 6

R (18) → (+1) → 19

OCTOBER = 16421163619