? primepi(nextprime(4000000453))
%25 = 189961830
? primepi(nextprime(4000000454))
*** at top-level: primepi(nextprime(40
*** ^--------------------
*** primepi: bug in PARI/GP (Segmentation Fault), please report
*** Break loop: type 'break' to go back to GP
break> break
? nextprime(4000000454)
%26 = 4000000483
?
nextprime(4000000483)
%27 = 4000000483
? nextprime(4000000484)
%28 = 4000000531
Maybe this shows that it is not the physical memory limit but a software bug?