18981728 has 12 divisors (see below), whose sum is σ = 37370340. Its totient is φ = 9490848.

The previous prime is 18981727. The next prime is 18981731. The reversal of 18981728 is 82718981.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18981727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 296558 + ... + 296621.

It is an arithmetic number, because the mean of its divisors is an integer number (3114195).

Almost surely, 2^18981728 is an apocalyptic number.

It is an amenable number.

18981728 is a deficient number, since it is larger than the sum of its proper divisors (18388612).

18981728 is an equidigital number, since it uses as much as digits as its factorization.

18981728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 593189 (or 593181 counting only the distinct ones).

The product of its digits is 64512, while the sum is 44.

The square root of 18981728 is about 4356.8024972450. The cubic root of 18981728 is about 266.7545987794.

The spelling of 18981728 in words is "eighteen million, nine hundred eighty-one thousand, seven hundred twenty-eight".