1665838728 has 24 divisors (see below), whose sum is σ = 4511646750. Its totient is φ = 555279552.

The previous prime is 1665838711. The next prime is 1665838729. The reversal of 1665838728 is 8278385661.

It can be written as a sum of positive squares in only one way, i.e., 1445672484 + 220166244 = 38022^2 + 14838^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (1665838729) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11568253 + ... + 11568396.

Almost surely, 2^1665838728 is an apocalyptic number.

1665838728 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1665838728 is an abundant number, since it is smaller than the sum of its proper divisors (2845808022).

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

1665838728 is a wasteful number, since it uses less digits than its factorization.

1665838728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23136661 (or 23136654 counting only the distinct ones).

The product of its digits is 3870720, while the sum is 54.

The square root of 1665838728 is about 40814.6876504035. The cubic root of 1665838728 is about 1185.4347430119.

The spelling of 1665838728 in words is "one billion, six hundred sixty-five million, eight hundred thirty-eight thousand, seven hundred twenty-eight".