205321221 has 18 divisors (see below), whose sum is σ = 344996262. Its totient is φ = 117326160.

The previous prime is 205321219. The next prime is 205321241. The reversal of 205321221 is 122123502.

It can be written as a sum of positive squares in only one way, i.e., 156125025 + 49196196 = 12495^2 + 7014^2 .

It is not a de Polignac number, because 205321221 - 2¹ = 205321219 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 205321194 and 205321203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205321211) 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 in 17 ways as a sum of consecutive naturals, for example, 232350 + ... + 233231.

It is an arithmetic number, because the mean of its divisors is an integer number (19166459).

Almost surely, 2^205321221 is an apocalyptic number.

205321221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

205321221 is a deficient number, since it is larger than the sum of its proper divisors (139675041).

205321221 is a wasteful number, since it uses less digits than its factorization.

205321221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 465601 (or 465591 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 205321221 is about 14329.0341963441. The cubic root of 205321221 is about 589.9446668399.

Adding to 205321221 its reverse (122123502), we get a palindrome (327444723).

The spelling of 205321221 in words is "two hundred five million, three hundred twenty-one thousand, two hundred twenty-one".