821857943 has 2 divisors, whose sum is σ = 821857944. Its totient is φ = 821857942.

The previous prime is 821857913. The next prime is 821857961. The reversal of 821857943 is 349758128.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 821857943 - 2¹⁸ = 821595799 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821857903) 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, 410928971 + 410928972.

It is an arithmetic number, because the mean of its divisors is an integer number (410928972).

Almost surely, 2^821857943 is an apocalyptic number.

821857943 is a deficient number, since it is larger than the sum of its proper divisors (1).

821857943 is an equidigital number, since it uses as much as digits as its factorization.

821857943 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 483840, while the sum is 47.

The square root of 821857943 is about 28668.0648631888. The cubic root of 821857943 is about 936.6965463015.

The spelling of 821857943 in words is "eight hundred twenty-one million, eight hundred fifty-seven thousand, nine hundred forty-three".