216680221 has 2 divisors, whose sum is σ = 216680222. Its totient is φ = 216680220.

The previous prime is 216680209. The next prime is 216680287. The reversal of 216680221 is 122086612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 216531225 + 148996 = 14715^2 + 386^2 .

It is a cyclic number.

It is not a de Polignac number, because 216680221 - 2²¹ = 214583069 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 216680221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216683221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108340110 + 108340111.

It is an arithmetic number, because the mean of its divisors is an integer number (108340111).

Almost surely, 2^216680221 is an apocalyptic number.

It is an amenable number.

216680221 is a deficient number, since it is larger than the sum of its proper divisors (1).

216680221 is an equidigital number, since it uses as much as digits as its factorization.

216680221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 216680221 is about 14720.0618544896. The cubic root of 216680221 is about 600.6291742616.

The spelling of 216680221 in words is "two hundred sixteen million, six hundred eighty thousand, two hundred twenty-one".