206631221 has 2 divisors, whose sum is σ = 206631222. Its totient is φ = 206631220.

The previous prime is 206631167. The next prime is 206631301. The reversal of 206631221 is 122136602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 199798225 + 6832996 = 14135^2 + 2614^2 .

It is a cyclic number.

It is not a de Polignac number, because 206631221 - 2¹⁰ = 206630197 is a prime.

It is a super-2 number, since 2×206631221² = 85392922983901682, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206631121) 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, 103315610 + 103315611.

It is an arithmetic number, because the mean of its divisors is an integer number (103315611).

Almost surely, 2^206631221 is an apocalyptic number.

It is an amenable number.

206631221 is a deficient number, since it is larger than the sum of its proper divisors (1).

206631221 is an equidigital number, since it uses as much as digits as its factorization.

206631221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 206631221 is about 14374.6729006263. The cubic root of 206631221 is about 591.1966720329.

Adding to 206631221 its reverse (122136602), we get a palindrome (328767823).

The spelling of 206631221 in words is "two hundred six million, six hundred thirty-one thousand, two hundred twenty-one".