721801 = 601x1201, that's already a little bigger, let's see if i can find some pseudoprimes to base 2,3,5,7 with only factors bigger than 7000...
Also:
A number n is a pseudoprime to the base b if b^n1 is congruent to 1 modulo n.
A Carmichael number is a composite number n such that b^n1 is congruent to 1 modulo n for every b that is relatively prime to n.
So we are talking about composite numbers that are pseudoprime to bases 2,3,5 and 7 ... this are not necessarily Carmichael numbers.
michael
