257564821 has 2 divisors, whose sum is σ = 257564822. Its totient is φ = 257564820.

The previous prime is 257564767. The next prime is 257564831. The reversal of 257564821 is 128465752.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 166152100 + 91412721 = 12890^2 + 9561^2 .

It is a cyclic number.

It is not a de Polignac number, because 257564821 - 2⁷ = 257564693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257564831) 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, 128782410 + 128782411.

It is an arithmetic number, because the mean of its divisors is an integer number (128782411).

Almost surely, 2^257564821 is an apocalyptic number.

It is an amenable number.

257564821 is a deficient number, since it is larger than the sum of its proper divisors (1).

257564821 is an equidigital number, since it uses as much as digits as its factorization.

257564821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 134400, while the sum is 40.

The square root of 257564821 is about 16048.8261564514. The cubic root of 257564821 is about 636.2515428728.

The spelling of 257564821 in words is "two hundred fifty-seven million, five hundred sixty-four thousand, eight hundred twenty-one".