665566668 has 72 divisors (see below), whose sum is σ = 1816214400. Its totient is φ = 204293376.

The previous prime is 665566661. The next prime is 665566673. The reversal of 665566668 is 866665566.

It is not an unprimeable number, because it can be changed into a prime (665566661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 222688 + ... + 225656.

It is an arithmetic number, because the mean of its divisors is an integer number (25225200).

Almost surely, 2^665566668 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665566668, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (908107200).

665566668 is an abundant number, since it is smaller than the sum of its proper divisors (1150647732).

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

665566668 is a wasteful number, since it uses less digits than its factorization.

665566668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3471 (or 3466 counting only the distinct ones).

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

The square root of 665566668 is about 25798.5787980656. The cubic root of 665566668 is about 873.0997315631.

The spelling of 665566668 in words is "six hundred sixty-five million, five hundred sixty-six thousand, six hundred sixty-eight".