18081728 has 28 divisors (see below), whose sum is σ = 41007792. Its totient is φ = 7749120.

The previous prime is 18081691. The next prime is 18081733. The reversal of 18081728 is 82718081.

It is a tau number, because it is divible by the number of its divisors (28).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19733 + ... + 20628.

It is an arithmetic number, because the mean of its divisors is an integer number (1464564).

Almost surely, 2^18081728 is an apocalyptic number.

It is an amenable number.

18081728 is an abundant number, since it is smaller than the sum of its proper divisors (22926064).

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

18081728 is an equidigital number, since it uses as much as digits as its factorization.

18081728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40380 (or 40370 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 35.

The square root of 18081728 is about 4252.2615159465. The cubic root of 18081728 is about 262.4701849735.

The spelling of 18081728 in words is "eighteen million, eighty-one thousand, seven hundred twenty-eight".