18221518 has 16 divisors (see below), whose sum is σ = 33074784. Its totient is φ = 7349760.

The previous prime is 18221509. The next prime is 18221519. The reversal of 18221518 is 81512281.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18221519) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 38043 + ... + 38518.

It is an arithmetic number, because the mean of its divisors is an integer number (2067174).

Almost surely, 2^18221518 is an apocalyptic number.

18221518 is a deficient number, since it is larger than the sum of its proper divisors (14853266).

18221518 is a wasteful number, since it uses less digits than its factorization.

18221518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76587.

The product of its digits is 1280, while the sum is 28.

The square root of 18221518 is about 4268.6670050497. The cubic root of 18221518 is about 263.1448358165.

Adding to 18221518 its reverse (81512281), we get a palindrome (99733799).

The spelling of 18221518 in words is "eighteen million, two hundred twenty-one thousand, five hundred eighteen".