18117216 has 96 divisors (see below), whose sum is σ = 56941920. Its totient is φ = 5571072.

The previous prime is 18117191. The next prime is 18117227. The reversal of 18117216 is 61271181.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 18117216.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10426 + ... + 12038.

It is an arithmetic number, because the mean of its divisors is an integer number (593145).

Almost surely, 2^18117216 is an apocalyptic number.

18117216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18117216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28470960).

18117216 is an abundant number, since it is smaller than the sum of its proper divisors (38824704).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18117216 is a wasteful number, since it uses less digits than its factorization.

18117216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1645 (or 1631 counting only the distinct ones).

The product of its digits is 672, while the sum is 27.

The square root of 18117216 is about 4256.4323088709. The cubic root of 18117216 is about 262.6417846283.

Adding to 18117216 its reverse (61271181), we get a palindrome (79388397).

The spelling of 18117216 in words is "eighteen million, one hundred seventeen thousand, two hundred sixteen".