18221616 has 60 divisors (see below), whose sum is σ = 58283472. Its totient is φ = 5205888.

The previous prime is 18221611. The next prime is 18221629. The reversal of 18221616 is 61612281.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 18221616.

It is not an unprimeable number, because it can be changed into a prime (18221611) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8031 + ... + 10046.

Almost surely, 2^18221616 is an apocalyptic number.

18221616 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

18221616 is an abundant number, since it is smaller than the sum of its proper divisors (40061856).

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

18221616 is a wasteful number, since it uses less digits than its factorization.

18221616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18098 (or 18089 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 18221616 is about 4268.6784840276. The cubic root of 18221616 is about 263.1453075692.

Adding to 18221616 its reverse (61612281), we get a palindrome (79833897).

The spelling of 18221616 in words is "eighteen million, two hundred twenty-one thousand, six hundred sixteen".