821381573 has 2 divisors, whose sum is σ = 821381574. Its totient is φ = 821381572.

The previous prime is 821381569. The next prime is 821381581. The reversal of 821381573 is 375183128.

It is a happy number.

821381573 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 448041889 + 373339684 = 21167^2 + 19322^2 .

It is a cyclic number.

It is not a de Polignac number, because 821381573 - 2² = 821381569 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821381593) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410690786 + 410690787.

It is an arithmetic number, because the mean of its divisors is an integer number (410690787).

Almost surely, 2^821381573 is an apocalyptic number.

It is an amenable number.

821381573 is a deficient number, since it is larger than the sum of its proper divisors (1).

821381573 is an equidigital number, since it uses as much as digits as its factorization.

821381573 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40320, while the sum is 38.

The square root of 821381573 is about 28659.7552850683. The cubic root of 821381573 is about 936.5155335212.

The spelling of 821381573 in words is "eight hundred twenty-one million, three hundred eighty-one thousand, five hundred seventy-three".