665605666 has 16 divisors (see below), whose sum is σ = 1099169280. Its totient is φ = 299771280.

The previous prime is 665605639. The next prime is 665605693. The reversal of 665605666 is 666506566.

It is an interprime number because it is at equal distance from previous prime (665605639) and next prime (665605693).

It is a super-2 number, since 2×665605666² = 886061805222607112, which contains 22 as substring.

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, 136386 + ... + 141181.

It is an arithmetic number, because the mean of its divisors is an integer number (68698080).

Almost surely, 2^665605666 is an apocalyptic number.

665605666 is a deficient number, since it is larger than the sum of its proper divisors (433563614).

665605666 is a wasteful number, since it uses less digits than its factorization.

665605666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277689.

The product of its (nonzero) digits is 1166400, while the sum is 46.

The square root of 665605666 is about 25799.3346038226. The cubic root of 665605666 is about 873.1167839387.

The spelling of 665605666 in words is "six hundred sixty-five million, six hundred five thousand, six hundred sixty-six".