1666666728 has 96 divisors (see below), whose sum is σ = 4655851200. Its totient is φ = 538272000.

The previous prime is 1666666711. The next prime is 1666666753. The reversal of 1666666728 is 8276666661.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 443883 + ... + 447621.

It is an arithmetic number, because the mean of its divisors is an integer number (48498450).

Almost surely, 2^1666666728 is an apocalyptic number.

1666666728 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 1666666728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2327925600).

1666666728 is an abundant number, since it is smaller than the sum of its proper divisors (2989184472).

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

1666666728 is a wasteful number, since it uses less digits than its factorization.

1666666728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3943 (or 3936 counting only the distinct ones).

The product of its digits is 5225472, while the sum is 54.

The square root of 1666666728 is about 40824.8297975631. The cubic root of 1666666728 is about 1185.6311160404.

The spelling of 1666666728 in words is "one billion, six hundred sixty-six million, six hundred sixty-six thousand, seven hundred twenty-eight".