18321228 has 84 divisors (see below), whose sum is σ = 49333648. Its totient is φ = 5948640.

The previous prime is 18321203. The next prime is 18321229. The reversal of 18321228 is 82212381.

It is a super-3 number, since 3×18321228³ (a number of 23 digits) contains 333 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (18321229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 177825 + ... + 177927.

Almost surely, 2^18321228 is an apocalyptic number.

18321228 is a gapful number since it is divisible by the number (18) 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 18321228, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24666824).

18321228 is an abundant number, since it is smaller than the sum of its proper divisors (31012420).

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

18321228 is a wasteful number, since it uses less digits than its factorization.

18321228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186 (or 169 counting only the distinct ones).

The product of its digits is 1536, while the sum is 27.

The square root of 18321228 is about 4280.3303610820. The cubic root of 18321228 is about 263.6239480623.

The spelling of 18321228 in words is "eighteen million, three hundred twenty-one thousand, two hundred twenty-eight".