Update: And here's my cheat sheet:

use Math::Pari qw/ primes nextprime isprime factor divisors /;

$P = primes(10);
print "First ten primes: @$P$/";

$D = divisors(100);
print "Divisors of 100: @$D$/";

$p = nextprime(100); 
print "next prime greater or equal to 100: $p$/";

$i = isprime(1680588011350901);
print "1680588011350901 is ", ($i?'':'not '), "prime$/";

$F = factor("10^100-1");
print "googol - 1 = ", join( "$/           * " ,
        map( { "$F->[0][$_]^$F->[1][$_]" } 0 .. $#{$F->[0]} )
      ), $/;

__END__
First ten primes: 2 3 5 7 11 13 17 19 23 29
Divisors of 100: 1 2 4 5 10 20 25 50 100
next prime greater or equal to 100: 101
1680588011350901 is  prime
googol - 1 = 3^2
           * 11^1
           * 41^1
           * 101^1
           * 251^1
           * 271^1
           * 3541^1
           * 5051^1
           * 9091^1
           * 21401^1
           * 25601^1
           * 27961^1
           * 60101^1
           * 7019801^1
           * 182521213001^1
           * 14103673319201^1
           * 78875943472201^1
           * 1680588011350901^1
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