16661218 has 16 divisors (see below), whose sum is σ = 29170944. Its totient is φ = 6988320.

The previous prime is 16661213. The next prime is 16661221. The reversal of 16661218 is 81216661.

It is a self number, because there is not a number n which added to its sum of digits gives 16661218.

It is not an unprimeable number, because it can be changed into a prime (16661213) 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, 12003 + ... + 13318.

It is an arithmetic number, because the mean of its divisors is an integer number (1823184).

Almost surely, 2^16661218 is an apocalyptic number.

16661218 is a deficient number, since it is larger than the sum of its proper divisors (12509726).

16661218 is a wasteful number, since it uses less digits than its factorization.

16661218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25377.

The product of its digits is 3456, while the sum is 31.

The square root of 16661218 is about 4081.8155274338. The cubic root of 16661218 is about 255.4086386662.

Adding to 16661218 its reverse (81216661), we get a palindrome (97877879).

The spelling of 16661218 in words is "sixteen million, six hundred sixty-one thousand, two hundred eighteen".