665686566 has 16 divisors (see below), whose sum is σ = 1479303600. Its totient is φ = 221895504.

The previous prime is 665686559. The next prime is 665686577.

665686566 is nontrivially palindromic in base 10.

665686566 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (54), and also a Moran number because the ratio is a prime number: 12327529 = 665686566 / (6 + 6 + 5 + 6 + 8 + 6 + 5 + 6 + 6).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6163711 + ... + 6163818.

It is an arithmetic number, because the mean of its divisors is an integer number (92456475).

Almost surely, 2^665686566 is an apocalyptic number.

665686566 is an abundant number, since it is smaller than the sum of its proper divisors (813617034).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

665686566 is a wasteful number, since it uses less digits than its factorization.

665686566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12327540 (or 12327534 counting only the distinct ones).

The product of its digits is 9331200, while the sum is 54.

The square root of 665686566 is about 25800.9024260780. The cubic root of 665686566 is about 873.1521563771.

The spelling of 665686566 in words is "six hundred sixty-five million, six hundred eighty-six thousand, five hundred sixty-six".