666601566 has 16 divisors (see below), whose sum is σ = 1364208384. Its totient is φ = 217032984.

The previous prime is 666601531. The next prime is 666601589. The reversal of 666601566 is 665106666.

It is a congruent number.

It is an unprimeable number.

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, 1291606 + ... + 1292121.

It is an arithmetic number, because the mean of its divisors is an integer number (85263024).

Almost surely, 2^666601566 is an apocalyptic number.

666601566 is an abundant number, since it is smaller than the sum of its proper divisors (697606818).

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

666601566 is a wasteful number, since it uses less digits than its factorization.

666601566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2583775.

The product of its (nonzero) digits is 233280, while the sum is 42.

The square root of 666601566 is about 25818.6282749491. The cubic root of 666601566 is about 873.5520284753.

The spelling of 666601566 in words is "six hundred sixty-six million, six hundred one thousand, five hundred sixty-six".