18721028 has 12 divisors (see below), whose sum is σ = 32842572. Its totient is φ = 9337440.

The previous prime is 18721009. The next prime is 18721033. The reversal of 18721028 is 82012781.

It can be written as a sum of positive squares in 2 ways, for example, as 760384 + 17960644 = 872^2 + 4238^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3875 + ... + 7242.

It is an arithmetic number, because the mean of its divisors is an integer number (2736881).

Almost surely, 2^18721028 is an apocalyptic number.

It is an amenable number.

18721028 is a deficient number, since it is larger than the sum of its proper divisors (14121544).

18721028 is a wasteful number, since it uses less digits than its factorization.

18721028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11542 (or 11540 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 18721028 is about 4326.7803272179. The cubic root of 18721028 is about 265.5277391181.

The spelling of 18721028 in words is "eighteen million, seven hundred twenty-one thousand, twenty-eight".