18021788 has 48 divisors (see below), whose sum is σ = 34836480. Its totient is φ = 8131200.

The previous prime is 18021781. The next prime is 18021791. The reversal of 18021788 is 88712081.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18021781) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 202448 + ... + 202536.

It is an arithmetic number, because the mean of its divisors is an integer number (725760).

Almost surely, 2^18021788 is an apocalyptic number.

It is an amenable number.

18021788 is a deficient number, since it is larger than the sum of its proper divisors (16814692).

18021788 is a wasteful number, since it uses less digits than its factorization.

18021788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218 (or 216 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 35.

The square root of 18021788 is about 4245.2076509872. The cubic root of 18021788 is about 262.1798388466.

The spelling of 18021788 in words is "eighteen million, twenty-one thousand, seven hundred eighty-eight".