857236021 has 2 divisors, whose sum is σ = 857236022. Its totient is φ = 857236020.

The previous prime is 857235997. The next prime is 857236043. The reversal of 857236021 is 120632758.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 677300625 + 179935396 = 26025^2 + 13414^2 .

It is a cyclic number.

It is not a de Polignac number, because 857236021 - 2⁷ = 857235893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (857236421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428618010 + 428618011.

It is an arithmetic number, because the mean of its divisors is an integer number (428618011).

Almost surely, 2^857236021 is an apocalyptic number.

It is an amenable number.

857236021 is a deficient number, since it is larger than the sum of its proper divisors (1).

857236021 is an equidigital number, since it uses as much as digits as its factorization.

857236021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20160, while the sum is 34.

The square root of 857236021 is about 29278.5932209866. The cubic root of 857236021 is about 949.9486661089.

Adding to 857236021 its reverse (120632758), we get a palindrome (977868779).

The spelling of 857236021 in words is "eight hundred fifty-seven million, two hundred thirty-six thousand, twenty-one".