864215221 has 2 divisors, whose sum is σ = 864215222. Its totient is φ = 864215220.

The previous prime is 864215203. The next prime is 864215239. The reversal of 864215221 is 122512468.

It is a balanced prime because it is at equal distance from previous prime (864215203) and next prime (864215239).

It can be written as a sum of positive squares in only one way, i.e., 805140625 + 59074596 = 28375^2 + 7686^2 .

It is a cyclic number.

It is not a de Polignac number, because 864215221 - 2¹⁷ = 864084149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (864215251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432107610 + 432107611.

It is an arithmetic number, because the mean of its divisors is an integer number (432107611).

Almost surely, 2^864215221 is an apocalyptic number.

It is an amenable number.

864215221 is a deficient number, since it is larger than the sum of its proper divisors (1).

864215221 is an equidigital number, since it uses as much as digits as its factorization.

864215221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7680, while the sum is 31.

The square root of 864215221 is about 29397.5376689953. The cubic root of 864215221 is about 952.5197084213.

Adding to 864215221 its reverse (122512468), we get a palindrome (986727689).

The spelling of 864215221 in words is "eight hundred sixty-four million, two hundred fifteen thousand, two hundred twenty-one".