18561218 has 32 divisors (see below), whose sum is σ = 31449600. Its totient is φ = 8156736.

The previous prime is 18561209. The next prime is 18561227. The reversal of 18561218 is 81216581.

It is an interprime number because it is at equal distance from previous prime (18561209) and next prime (18561227).

It is an alternating number because its digits alternate between odd and even.

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 15 ways as a sum of consecutive naturals, for example, 77543 + ... + 77781.

It is an arithmetic number, because the mean of its divisors is an integer number (982800).

Almost surely, 2^18561218 is an apocalyptic number.

18561218 is a deficient number, since it is larger than the sum of its proper divisors (12888382).

18561218 is a wasteful number, since it uses less digits than its factorization.

18561218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 386.

The product of its digits is 3840, while the sum is 32.

The square root of 18561218 is about 4308.2732039647. The cubic root of 18561218 is about 264.7700295121.

Adding to 18561218 its reverse (81216581), we get a palindrome (99777799).

The spelling of 18561218 in words is "eighteen million, five hundred sixty-one thousand, two hundred eighteen".