665689986566 has 32 divisors (see below), whose sum is σ = 1108011018240. Its totient is φ = 297434988000.

The previous prime is 665689986553. The next prime is 665689986601.

It is a happy number.

665689986566 is nontrivially palindromic in base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 768806 + ... + 1386521.

It is an arithmetic number, because the mean of its divisors is an integer number (34625344320).

Almost surely, 2^665689986566 is an apocalyptic number.

665689986566 is a deficient number, since it is larger than the sum of its proper divisors (442321031674).

665689986566 is a wasteful number, since it uses less digits than its factorization.

665689986566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2155580.

The product of its digits is 6046617600, while the sum is 80.

The spelling of 665689986566 in words is "six hundred sixty-five billion, six hundred eighty-nine million, nine hundred eighty-six thousand, five hundred sixty-six".