18665216 has 18 divisors (see below), whose sum is σ = 37258032. Its totient is φ = 9332480.

The previous prime is 18665203. The next prime is 18665219. The reversal of 18665216 is 61256681.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18665219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36200 + ... + 36711.

Almost surely, 2^18665216 is an apocalyptic number.

18665216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

18665216 is a deficient number, since it is larger than the sum of its proper divisors (18592816).

18665216 is an frugal number, since it uses more digits than its factorization.

18665216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72927 (or 72913 counting only the distinct ones).

The product of its digits is 17280, while the sum is 35.

The square root of 18665216 is about 4320.3259136320. The cubic root of 18665216 is about 265.2636085798.

It can be divided in two parts, 18665 and 216, that added together give a palindrome (18881).

The spelling of 18665216 in words is "eighteen million, six hundred sixty-five thousand, two hundred sixteen".