665657666 has 16 divisors (see below), whose sum is σ = 1051591200. Its totient is φ = 315145728.

The previous prime is 665657633. The next prime is 665657689. The reversal of 665657666 is 666756566.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 98690 + ... + 105218.

It is an arithmetic number, because the mean of its divisors is an integer number (65724450).

Almost surely, 2^665657666 is an apocalyptic number.

665657666 is a deficient number, since it is larger than the sum of its proper divisors (385933534).

665657666 is a wasteful number, since it uses less digits than its factorization.

665657666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9233.

The product of its digits is 8164800, while the sum is 53.

The square root of 665657666 is about 25800.3423620695. The cubic root of 665657666 is about 873.1395205693.

The spelling of 665657666 in words is "six hundred sixty-five million, six hundred fifty-seven thousand, six hundred sixty-six".