166565111555 has 4 divisors (see below), whose sum is σ = 199878133872. Its totient is φ = 133252089240.

The previous prime is 166565111519. The next prime is 166565111569. The reversal of 166565111555 is 555111565661.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 166565111555 - 2⁶ = 166565111491 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16656511151 + ... + 16656511160.

It is an arithmetic number, because the mean of its divisors is an integer number (49969533468).

Almost surely, 2^166565111555 is an apocalyptic number.

166565111555 is a deficient number, since it is larger than the sum of its proper divisors (33313022317).

166565111555 is an equidigital number, since it uses as much as digits as its factorization.

166565111555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33313022316.

The product of its digits is 675000, while the sum is 47.

The spelling of 166565111555 in words is "one hundred sixty-six billion, five hundred sixty-five million, one hundred eleven thousand, five hundred fifty-five".