66556877865566 has 16 divisors (see below), whose sum is σ = 111567626756208. Its totient is φ = 29515245172800.

The previous prime is 66556877865547. The next prime is 66556877865619.

66556877865566 is nontrivially palindromic in base 10.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36894055565 + ... + 36894057368.

It is an arithmetic number, because the mean of its divisors is an integer number (6972976672263).

Almost surely, 2^{66556877865566} is an apocalyptic number.

66556877865566 is a deficient number, since it is larger than the sum of its proper divisors (45010748890642).

66556877865566 is a wasteful number, since it uses less digits than its factorization.

66556877865566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73788112987.

The product of its digits is 91445760000, while the sum is 86.

The spelling of 66556877865566 in words is "sixty-six trillion, five hundred fifty-six billion, eight hundred seventy-seven million, eight hundred sixty-five thousand, five hundred sixty-six".