18518521 has 12 divisors (see below), whose sum is σ = 22676880. Its totient is φ = 15036840.

The previous prime is 18518503. The next prime is 18518531. The reversal of 18518521 is 12581581.

It is not a de Polignac number, because 18518521 - 2⁷ = 18518393 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18518531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9015 + ... + 10876.

It is an arithmetic number, because the mean of its divisors is an integer number (1889740).

Almost surely, 2^18518521 is an apocalyptic number.

It is an amenable number.

18518521 is a deficient number, since it is larger than the sum of its proper divisors (4158359).

18518521 is a wasteful number, since it uses less digits than its factorization.

18518521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19924 (or 19917 counting only the distinct ones).

The product of its digits is 3200, while the sum is 31.

The square root of 18518521 is about 4303.3151174414. The cubic root of 18518521 is about 264.5668538120.

The spelling of 18518521 in words is "eighteen million, five hundred eighteen thousand, five hundred twenty-one".