205616221 has 2 divisors, whose sum is σ = 205616222. Its totient is φ = 205616220.

The previous prime is 205616219. The next prime is 205616261. The reversal of 205616221 is 122616502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 187005625 + 18610596 = 13675^2 + 4314^2 .

It is a cyclic number.

It is not a de Polignac number, because 205616221 - 2¹ = 205616219 is a prime.

Together with 205616219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205616261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102808110 + 102808111.

It is an arithmetic number, because the mean of its divisors is an integer number (102808111).

Almost surely, 2^205616221 is an apocalyptic number.

It is an amenable number.

205616221 is a deficient number, since it is larger than the sum of its proper divisors (1).

205616221 is an equidigital number, since it uses as much as digits as its factorization.

205616221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 205616221 is about 14339.3242867298. The cubic root of 205616221 is about 590.2270705021.

The spelling of 205616221 in words is "two hundred five million, six hundred sixteen thousand, two hundred twenty-one".