819320221 has 2 divisors, whose sum is σ = 819320222. Its totient is φ = 819320220.

The previous prime is 819320149. The next prime is 819320233. The reversal of 819320221 is 122023918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 811452196 + 7868025 = 28486^2 + 2805^2 .

It is a cyclic number.

It is not a de Polignac number, because 819320221 - 2²³ = 810931613 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 819320221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (819320251) 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, 409660110 + 409660111.

It is an arithmetic number, because the mean of its divisors is an integer number (409660111).

Almost surely, 2^819320221 is an apocalyptic number.

It is an amenable number.

819320221 is a deficient number, since it is larger than the sum of its proper divisors (1).

819320221 is an equidigital number, since it uses as much as digits as its factorization.

819320221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 819320221 is about 28623.7702093907. The cubic root of 819320221 is about 935.7314459080.

The spelling of 819320221 in words is "eight hundred nineteen million, three hundred twenty thousand, two hundred twenty-one".