18721328 has 20 divisors (see below), whose sum is σ = 36682920. Its totient is φ = 9254784.

The previous prime is 18721309. The next prime is 18721331. The reversal of 18721328 is 82312781.

It is a junction number, because it is equal to n+sod(n) for n = 18721294 and 18721303.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 5150 + ... + 7997.

It is an arithmetic number, because the mean of its divisors is an integer number (1834146).

Almost surely, 2^18721328 is an apocalyptic number.

It is an amenable number.

18721328 is a deficient number, since it is larger than the sum of its proper divisors (17961592).

18721328 is a wasteful number, since it uses less digits than its factorization.

18721328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13244 (or 13238 counting only the distinct ones).

The product of its digits is 5376, while the sum is 32.

The square root of 18721328 is about 4326.8149948894. The cubic root of 18721328 is about 265.5291574500.

The spelling of 18721328 in words is "eighteen million, seven hundred twenty-one thousand, three hundred twenty-eight".