18321664 has 18 divisors (see below), whose sum is σ = 36572270. Its totient is φ = 9160704.

The previous prime is 18321661. The next prime is 18321673. The reversal of 18321664 is 46612381.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 17305600 + 1016064 = 4160^2 + 1008^2 .

It is not an unprimeable number, because it can be changed into a prime (18321661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35529 + ... + 36040.

Almost surely, 2^18321664 is an apocalyptic number.

It is an amenable number.

18321664 is a deficient number, since it is larger than the sum of its proper divisors (18250606).

18321664 is an frugal number, since it uses more digits than its factorization.

18321664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71585 (or 71571 counting only the distinct ones).

The product of its digits is 6912, while the sum is 31.

The square root of 18321664 is about 4280.3812914272. The cubic root of 18321664 is about 263.6260392455.

The spelling of 18321664 in words is "eighteen million, three hundred twenty-one thousand, six hundred sixty-four".