18221864 has 8 divisors (see below), whose sum is σ = 34166010. Its totient is φ = 9110928.

The previous prime is 18221851. The next prime is 18221869. The reversal of 18221864 is 46812281.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 12180100 + 6041764 = 3490^2 + 2458^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a self number, because there is not a number n which added to its sum of digits gives 18221864.

It is not an unprimeable number, because it can be changed into a prime (18221869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1138859 + ... + 1138874.

Almost surely, 2^18221864 is an apocalyptic number.

It is an amenable number.

18221864 is a deficient number, since it is larger than the sum of its proper divisors (15944146).

18221864 is a wasteful number, since it uses less digits than its factorization.

18221864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2277739 (or 2277735 counting only the distinct ones).

The product of its digits is 6144, while the sum is 32.

The square root of 18221864 is about 4268.7075327317. The cubic root of 18221864 is about 263.1465013846.

The spelling of 18221864 in words is "eighteen million, two hundred twenty-one thousand, eight hundred sixty-four".