21 - each number in the series increases by the series 1,2,3,4,5.... Whereby 6 and 7 are separated by 1, 7 and 9 are separated by 2, 9 and 12 are separated by 3, 12 and 16 are separated by 4, so the next in the series would be 21 (16 and 21 are separated by 5).
22
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!
8
243
20
25
73791170
108