206221581221 has 2 divisors, whose sum is σ = 206221581222. Its totient is φ = 206221581220.

The previous prime is 206221581187. The next prime is 206221581253. The reversal of 206221581221 is 122185122602.

It is an a-pointer prime, because the next prime (206221581253) can be obtained adding 206221581221 to its sum of digits (32).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 204362764225 + 1858816996 = 452065^2 + 43114^2 .

It is a cyclic number.

It is not a de Polignac number, because 206221581221 - 2¹⁸ = 206221319077 is a prime.

It is a super-2 number, since 2×206221581221² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206221581271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103110790610 + 103110790611.

It is an arithmetic number, because the mean of its divisors is an integer number (103110790611).

Almost surely, 2^206221581221 is an apocalyptic number.

It is an amenable number.

206221581221 is a deficient number, since it is larger than the sum of its proper divisors (1).

206221581221 is an equidigital number, since it uses as much as digits as its factorization.

206221581221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7680, while the sum is 32.

The spelling of 206221581221 in words is "two hundred six billion, two hundred twenty-one million, five hundred eighty-one thousand, two hundred twenty-one".