810215221 has 2 divisors, whose sum is σ = 810215222. Its totient is φ = 810215220.

The previous prime is 810215191. The next prime is 810215243. The reversal of 810215221 is 122512018.

810215221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an a-pointer prime, because the next prime (810215243) can be obtained adding 810215221 to its sum of digits (22).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 801512721 + 8702500 = 28311^2 + 2950^2 .

It is a cyclic number.

It is not a de Polignac number, because 810215221 - 2²⁷ = 675997493 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 810215192 and 810215201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (810215261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405107610 + 405107611.

It is an arithmetic number, because the mean of its divisors is an integer number (405107611).

Almost surely, 2^810215221 is an apocalyptic number.

It is an amenable number.

810215221 is a deficient number, since it is larger than the sum of its proper divisors (1).

810215221 is an equidigital number, since it uses as much as digits as its factorization.

810215221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 320, while the sum is 22.

The square root of 810215221 is about 28464.2797379452. The cubic root of 810215221 is about 932.2523051771.

Adding to 810215221 its reverse (122512018), we get a palindrome (932727239).

The spelling of 810215221 in words is "eight hundred ten million, two hundred fifteen thousand, two hundred twenty-one".