216365221 has 4 divisors (see below), whose sum is σ = 217263244. Its totient is φ = 215467200.

The previous prime is 216365203. The next prime is 216365249. The reversal of 216365221 is 122563612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 110481121 + 105884100 = 10511^2 + 10290^2 .

It is a cyclic number.

It is not a de Polignac number, because 216365221 - 2¹⁷ = 216234149 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 216365221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216365321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 448650 + ... + 449131.

It is an arithmetic number, because the mean of its divisors is an integer number (54315811).

Almost surely, 2^216365221 is an apocalyptic number.

It is an amenable number.

216365221 is a deficient number, since it is larger than the sum of its proper divisors (898023).

216365221 is an equidigital number, since it uses as much as digits as its factorization.

216365221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 898022.

The product of its digits is 4320, while the sum is 28.

The square root of 216365221 is about 14709.3582796803. The cubic root of 216365221 is about 600.3379771759.

The spelling of 216365221 in words is "two hundred sixteen million, three hundred sixty-five thousand, two hundred twenty-one".