668185728 has 128 divisors (see below), whose sum is σ = 2037258240. Its totient is φ = 190080000.

The previous prime is 668185669. The next prime is 668185747. The reversal of 668185728 is 827581866.

It is a tau number, because it is divible by the number of its divisors (128).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 889353 + ... + 890103.

It is an arithmetic number, because the mean of its divisors is an integer number (15916080).

Almost surely, 2^668185728 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 668185728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1018629120).

668185728 is an abundant number, since it is smaller than the sum of its proper divisors (1369072512).

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

668185728 is a wasteful number, since it uses less digits than its factorization.

668185728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1106 (or 1094 counting only the distinct ones).

The product of its digits is 1290240, while the sum is 51.

The square root of 668185728 is about 25849.2887329613. The cubic root of 668185728 is about 874.2434725690.

The spelling of 668185728 in words is "six hundred sixty-eight million, one hundred eighty-five thousand, seven hundred twenty-eight".