857280821 has 2 divisors, whose sum is σ = 857280822. Its totient is φ = 857280820.

The previous prime is 857280793. The next prime is 857280839. The reversal of 857280821 is 128082758.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 850363921 + 6916900 = 29161^2 + 2630^2 .

It is a cyclic number.

It is not a de Polignac number, because 857280821 - 2⁶ = 857280757 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 (857280881) 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, 428640410 + 428640411.

It is an arithmetic number, because the mean of its divisors is an integer number (428640411).

Almost surely, 2^857280821 is an apocalyptic number.

It is an amenable number.

857280821 is a deficient number, since it is larger than the sum of its proper divisors (1).

857280821 is an equidigital number, since it uses as much as digits as its factorization.

857280821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 71680, while the sum is 41.

The square root of 857280821 is about 29279.3582750715. The cubic root of 857280821 is about 949.9652142387.

The spelling of 857280821 in words is "eight hundred fifty-seven million, two hundred eighty thousand, eight hundred twenty-one".