ValueError: invalid literal for int() with base 10: ''

[snippsat]

Before doing any regex @keames,should first figure out what going on
Like using repr() that i will show later.

@ivinjjunior if i just copy your code from post and run it.
There can be a extra first blank line there,if you copied all in without enter after your post sentence.

with open('numbers.txt') as f:
    for line in f:
        line = line.strip()
        print(int(line))

Output:
2105301
2106301
2108701
2108801
2108901
2109101
2109201
2109501

To see all use repr(),here i just remove strip() then will see \n or any other problem that there can be with input file.

with open('numbers.txt') as f:
    for line in f:
        line = line
        print(repr(line))

'2105301\n'
'2106301\n'
'2108701\n'
'2108801\n'
'2108901\n'
'2109101\n'
'2109201\n'
'2109501'

My guess is that you have blank line in file,then cant try this.

with open('numbers.txt') as f:
    for line in f:
        line = line.strip()
        if line != '':           
            print(int(line))