216658728 has 144 divisors (see below), whose sum is σ = 694954260. Its totient is φ = 60572160.

The previous prime is 216658723. The next prime is 216658733. The reversal of 216658728 is 827856612.

216658728 is a `hidden beast` number, since 2 + 1 + 66 + 587 + 2 + 8 = 666.

It is an interprime number because it is at equal distance from previous prime (216658723) and next prime (216658733).

It can be written as a sum of positive squares in 2 ways, for example, as 216619524 + 39204 = 14718^2 + 198^2 .

It is not an unprimeable number, because it can be changed into a prime (216658723) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 112300 + ... + 114212.

Almost surely, 2^216658728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 216658728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (347477130).

216658728 is an abundant number, since it is smaller than the sum of its proper divisors (478295532).

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

216658728 is a wasteful number, since it uses less digits than its factorization.

216658728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1960 (or 1942 counting only the distinct ones).

The product of its digits is 322560, while the sum is 45.

The square root of 216658728 is about 14719.3317783111. The cubic root of 216658728 is about 600.6093143506.

The spelling of 216658728 in words is "two hundred sixteen million, six hundred fifty-eight thousand, seven hundred twenty-eight".