Adding to 666780 its product of nonzero digits (12096), we get a palindrome (678876).
It is an Ulam number.
It is a congruent number.
It is an unprimeable number.
666780 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
2666780 is an apocalyptic number.
666780 is a gapful number since it is divisible by the number (60) formed by its first and last digit.
It is an amenable number.
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
666780 is a wasteful number, since it uses less digits than its factorization.
666780 is an odious number, because the sum of its binary digits is odd.
The square root of 666780 is about 816.5659801878. The cubic root of 666780 is about 87.3629964824.
The spelling of 666780 in words is "six hundred sixty-six thousand, seven hundred eighty".