18685728 has 108 divisors (see below), whose sum is σ = 55798470. Its totient is φ = 6158592.

The previous prime is 18685727. The next prime is 18685739. The reversal of 18685728 is 82758681.

18685728 is a `hidden beast` number, since 18 + 68 + 572 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 17740944 + 944784 = 4212^2 + 972^2 .

It is a tau number, because it is divible by the number of its divisors (108).

It is not an unprimeable number, because it can be changed into a prime (18685727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 209908 + ... + 209996.

Almost surely, 2^18685728 is an apocalyptic number.

18685728 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 18685728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27899235).

18685728 is an abundant number, since it is smaller than the sum of its proper divisors (37112742).

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

18685728 is an frugal number, since it uses more digits than its factorization.

18685728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123 (or 94 counting only the distinct ones).

The product of its digits is 215040, while the sum is 45.

The square root of 18685728 is about 4322.6991567769. The cubic root of 18685728 is about 265.3607428286.

The spelling of 18685728 in words is "eighteen million, six hundred eighty-five thousand, seven hundred twenty-eight".