18631728 has 160 divisors (see below), whose sum is σ = 58924800. Its totient is φ = 5612544.

The previous prime is 18631727. The next prime is 18631733. The reversal of 18631728 is 82713681.

18631728 is a `hidden beast` number, since 18 + 631 + 7 + 2 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 18631692 and 18631701.

It is not an unprimeable number, because it can be changed into a prime (18631721) 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, 315763 + ... + 315821.

It is an arithmetic number, because the mean of its divisors is an integer number (368280).

Almost surely, 2^18631728 is an apocalyptic number.

18631728 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 18631728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29462400).

18631728 is an abundant number, since it is smaller than the sum of its proper divisors (40293072).

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

18631728 is a wasteful number, since it uses less digits than its factorization.

18631728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 124 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 18631728 is about 4316.4485401774. The cubic root of 18631728 is about 265.1048736445.

The spelling of 18631728 in words is "eighteen million, six hundred thirty-one thousand, seven hundred twenty-eight".