668728188 has 36 divisors (see below), whose sum is σ = 1694449848. Its totient is φ = 222374880.

The previous prime is 668728183. The next prime is 668728223. The reversal of 668728188 is 881827866.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668728183) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6906 + ... + 37217.

Almost surely, 2^668728188 is an apocalyptic number.

It is an amenable number.

668728188 is an abundant number, since it is smaller than the sum of its proper divisors (1025721660).

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

668728188 is a wasteful number, since it uses less digits than its factorization.

668728188 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44554 (or 44549 counting only the distinct ones).

The product of its digits is 2064384, while the sum is 54.

The square root of 668728188 is about 25859.7793494067. The cubic root of 668728188 is about 874.4799905588.

The spelling of 668728188 in words is "six hundred sixty-eight million, seven hundred twenty-eight thousand, one hundred eighty-eight".