665505566 has 24 divisors (see below), whose sum is σ = 1099104552. Its totient is φ = 301994000.

The previous prime is 665505553. The next prime is 665505583.

665505566 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 11 ways as a sum of consecutive naturals, for example, 167681 + ... + 171603.

It is an arithmetic number, because the mean of its divisors is an integer number (45796023).

Almost surely, 2^665505566 is an apocalyptic number.

665505566 is a deficient number, since it is larger than the sum of its proper divisors (433598986).

665505566 is a wasteful number, since it uses less digits than its factorization.

665505566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4648 (or 4637 counting only the distinct ones).

The product of its (nonzero) digits is 810000, while the sum is 44.

The square root of 665505566 is about 25797.3945583658. The cubic root of 665505566 is about 873.0730125907.

The spelling of 665505566 in words is "six hundred sixty-five million, five hundred five thousand, five hundred sixty-six".