import re
pattern = r"(?<!\S)\d+\b(?!€|\.\d)"
s = ("I have the following products 4526 and 4. The first one I paid $40 while the second one 30€. \n"
"Here the link for the discount of 3.99: https://w...content-available-to-author-only...d.coom/7574@5757\n")
print(re.findall(pattern, s))
aW1wb3J0IHJlCgpwYXR0ZXJuID0gciIoPzwhXFMpXGQrXGIoPyHigqx8XC5cZCkiCnMgPSAoIkkgaGF2ZSB0aGUgZm9sbG93aW5nIHByb2R1Y3RzIDQ1MjYgYW5kIDQuIFRoZSBmaXJzdCBvbmUgSSBwYWlkICQ0MCB3aGlsZSB0aGUgc2Vjb25kIG9uZSAzMOKCrC4gXG4iCgkiSGVyZSB0aGUgbGluayBmb3IgdGhlIGRpc2NvdW50IG9mIDMuOTk6IGh0dHBzOi8vdy4uLmNvbnRlbnQtYXZhaWxhYmxlLXRvLWF1dGhvci1vbmx5Li4uZC5jb29tLzc1NzRANTc1N1xuIikKCQpwcmludChyZS5maW5kYWxsKHBhdHRlcm4sIHMpKQ==