18131218 has 16 divisors (see below), whose sum is σ = 32085504. Its totient is φ = 7519680.

The previous prime is 18131209. The next prime is 18131219. The reversal of 18131218 is 81213181.

It is a junction number, because it is equal to n+sod(n) for n = 18131192 and 18131201.

It is not an unprimeable number, because it can be changed into a prime (18131219) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20455 + ... + 21322.

It is an arithmetic number, because the mean of its divisors is an integer number (2005344).

Almost surely, 2^18131218 is an apocalyptic number.

18131218 is a deficient number, since it is larger than the sum of its proper divisors (13954286).

18131218 is a wasteful number, since it uses less digits than its factorization.

18131218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41817.

The product of its digits is 384, while the sum is 25.

The square root of 18131218 is about 4258.0767959256. The cubic root of 18131218 is about 262.7094286357.

Adding to 18131218 its reverse (81213181), we get a palindrome (99344399).

The spelling of 18131218 in words is "eighteen million, one hundred thirty-one thousand, two hundred eighteen".