18031728 has 160 divisors (see below), whose sum is σ = 56996352. Its totient is φ = 4838400.

The previous prime is 18031721. The next prime is 18031729. The reversal of 18031728 is 82713081.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 18031695 and 18031704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18031721) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 253933 + ... + 254003.

Almost surely, 2^18031728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18031728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28498176).

18031728 is an abundant number, since it is smaller than the sum of its proper divisors (38964624).

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

18031728 is a wasteful number, since it uses less digits than its factorization.

18031728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143 (or 137 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 18031728 is about 4246.3782214965. The cubic root of 18031728 is about 262.2280321523.

The spelling of 18031728 in words is "eighteen million, thirty-one thousand, seven hundred twenty-eight".