666664668 has 126 divisors (see below), whose sum is σ = 1808512776. Its totient is φ = 214920864.

The previous prime is 666664643. The next prime is 666664679. The reversal of 666664668 is 866466666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 41 ways as a sum of consecutive naturals, for example, 3991921 + ... + 3992087.

It is an arithmetic number, because the mean of its divisors is an integer number (14353276).

Almost surely, 2^666664668 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 666664668, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (904256388).

666664668 is an abundant number, since it is smaller than the sum of its proper divisors (1141848108).

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

666664668 is a wasteful number, since it uses less digits than its factorization.

666664668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263 (or 209 counting only the distinct ones).

The product of its digits is 8957952, while the sum is 54.

The square root of 666664668 is about 25819.8502706735. The cubic root of 666664668 is about 873.5795917373.

The spelling of 666664668 in words is "six hundred sixty-six million, six hundred sixty-four thousand, six hundred sixty-eight".