1666189728 has 288 divisors, whose sum is σ = 5613753600. Its totient is φ = 468518400.

The previous prime is 1666189709. The next prime is 1666189793. The reversal of 1666189728 is 8279816661.

It is a tau number, because it is divible by the number of its divisors (288).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 9977101 + ... + 9977267.

It is an arithmetic number, because the mean of its divisors is an integer number (19492200).

Almost surely, 2^1666189728 is an apocalyptic number.

1666189728 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1666189728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2806876800).

1666189728 is an abundant number, since it is smaller than the sum of its proper divisors (3947563872).

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

1666189728 is a wasteful number, since it uses less digits than its factorization.

1666189728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305 (or 280 counting only the distinct ones).

The product of its digits is 1741824, while the sum is 54.

The square root of 1666189728 is about 40818.9873465768. The cubic root of 1666189728 is about 1185.5179960438.

The spelling of 1666189728 in words is "one billion, six hundred sixty-six million, one hundred eighty-nine thousand, seven hundred twenty-eight".