661565565166 has 16 divisors (see below), whose sum is σ = 1082599948080. Its totient is φ = 300701033280.

The previous prime is 661565565161. The next prime is 661565565203.

661565565166 is nontrivially palindromic in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 661565565166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661565565161) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 127840 + ... + 1157356.

It is an arithmetic number, because the mean of its divisors is an integer number (67662496755).

Almost surely, 2^661565565166 is an apocalyptic number.

661565565166 is a deficient number, since it is larger than the sum of its proper divisors (421034382914).

661565565166 is a wasteful number, since it uses less digits than its factorization.

661565565166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1058739.

The product of its digits is 29160000, while the sum is 58.

The spelling of 661565565166 in words is "six hundred sixty-one billion, five hundred sixty-five million, five hundred sixty-five thousand, one hundred sixty-six".