857128549 has 2 divisors, whose sum is σ = 857128550. Its totient is φ = 857128548.

The previous prime is 857128537. The next prime is 857128567. The reversal of 857128549 is 945821758.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 698544900 + 158583649 = 26430^2 + 12593^2 .

It is a cyclic number.

It is not a de Polignac number, because 857128549 - 2⁹ = 857128037 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (857128249) 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, 428564274 + 428564275.

It is an arithmetic number, because the mean of its divisors is an integer number (428564275).

Almost surely, 2^857128549 is an apocalyptic number.

It is an amenable number.

857128549 is a deficient number, since it is larger than the sum of its proper divisors (1).

857128549 is an equidigital number, since it uses as much as digits as its factorization.

857128549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 806400, while the sum is 49.

The square root of 857128549 is about 29276.7578293772. The cubic root of 857128549 is about 949.9089659768.

The spelling of 857128549 in words is "eight hundred fifty-seven million, one hundred twenty-eight thousand, five hundred forty-nine".