2218321728 has 504 divisors, whose sum is σ = 7968227904. Its totient is φ = 609638400.

The previous prime is 2218321723. The next prime is 2218321751. The reversal of 2218321728 is 8271238122.

It is a tau number, because it is divible by the number of its divisors (504).

It is a Harshad number since it is a multiple of its sum of digits (36).

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

It is a junction number, because it is equal to n+sod(n) for n = 2218321692 and 2218321701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2218321723) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 31243933 + ... + 31244003.

It is an arithmetic number, because the mean of its divisors is an integer number (15809976).

Almost surely, 2^2218321728 is an apocalyptic number.

2218321728 is a gapful number since it is divisible by the number (28) 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 2218321728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3984113952).

2218321728 is an abundant number, since it is smaller than the sum of its proper divisors (5749906176).

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

2218321728 is an equidigital number, since it uses as much as digits as its factorization.

2218321728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153 (or 124 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The square root of 2218321728 is about 47099.0629206145. The cubic root of 2218321728 is about 1304.1919373210.

The spelling of 2218321728 in words is "two billion, two hundred eighteen million, three hundred twenty-one thousand, seven hundred twenty-eight".