Assuming that series is 88, 87, 85, 81, 73, 57 the next number is 25.
The difference each time is twice the previous difference:
88 → 87 : 88 - 87 = 1
87 → 85 : 87 - 85 = 2 = 1 x 2
85 → 81 : 85 - 81 = 4 = 2 x 2
81 → 73 : 81 - 73 = 8 = 4 x 2
73 → 57 : 73 - 75 = 16 = 8 x 2
→ next difference is 16 x 2 = 32
→ next number is 57 - 32 = 25
59 is the next number in this series.
One number does not make a sequence (nor a series).
243
The next number is 1112.
10
59 is the next number in this series.
The next number in the series is 67.
A single number such as 61205041320 does not make a series.
A single number, such as 12848384 does not make a series.
One number does not make a sequence (nor a series).
There is no series of number: just one very large number!
73791170
20
8
243
25
108