216500221 has 4 divisors (see below), whose sum is σ = 247428832. Its totient is φ = 185571612.

The previous prime is 216500201. The next prime is 216500237. The reversal of 216500221 is 122005612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 216500221 - 2¹⁹ = 215975933 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216500201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15464295 + ... + 15464308.

It is an arithmetic number, because the mean of its divisors is an integer number (61857208).

Almost surely, 2^216500221 is an apocalyptic number.

It is an amenable number.

216500221 is a deficient number, since it is larger than the sum of its proper divisors (30928611).

216500221 is an equidigital number, since it uses as much as digits as its factorization.

216500221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30928610.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 216500221 is about 14713.9464794460. The cubic root of 216500221 is about 600.4628105115.

Adding to 216500221 its reverse (122005612), we get a palindrome (338505833).

The spelling of 216500221 in words is "two hundred sixteen million, five hundred thousand, two hundred twenty-one".