666688 has 28 divisors (see below), whose sum is σ = 1444752. Its totient is φ = 302720.

The previous prime is 666683. The next prime is 666697. The reversal of 666688 is 886666.

It is a plaindrome in base 10.

It is a zygodrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 666688.

It is not an unprimeable number, because it can be changed into a prime (666683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 231 + ... + 1177.

2⁶⁶⁶⁶⁸⁸ 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 666688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (722376).

666688 is an abundant number, since it is smaller than the sum of its proper divisors (778064).

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

666688 is a wasteful number, since it uses less digits than its factorization.

666688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 970 (or 960 counting only the distinct ones).

The product of its digits is 82944, while the sum is 40.

The square root of 666688 is about 816.5096447685. The cubic root of 666688 is about 87.3589782829.

The spelling of 666688 in words is "six hundred sixty-six thousand, six hundred eighty-eight".