216786221 has 2 divisors, whose sum is σ = 216786222. Its totient is φ = 216786220.

The previous prime is 216786203. The next prime is 216786239. The reversal of 216786221 is 122687612.

It is a balanced prime because it is at equal distance from previous prime (216786203) and next prime (216786239).

It can be written as a sum of positive squares in only one way, i.e., 115562500 + 101223721 = 10750^2 + 10061^2 .

It is a cyclic number.

It is not a de Polignac number, because 216786221 - 2²⁶ = 149677357 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216786821) 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, 108393110 + 108393111.

It is an arithmetic number, because the mean of its divisors is an integer number (108393111).

Almost surely, 2^216786221 is an apocalyptic number.

It is an amenable number.

216786221 is a deficient number, since it is larger than the sum of its proper divisors (1).

216786221 is an equidigital number, since it uses as much as digits as its factorization.

216786221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16128, while the sum is 35.

The square root of 216786221 is about 14723.6619426011. The cubic root of 216786221 is about 600.7271009252.

It can be divided in two parts, 2167 and 86221, that added together give a palindrome (88388).

The spelling of 216786221 in words is "two hundred sixteen million, seven hundred eighty-six thousand, two hundred twenty-one".