257821457 has 2 divisors, whose sum is σ = 257821458. Its totient is φ = 257821456.

The previous prime is 257821453. The next prime is 257821483. The reversal of 257821457 is 754128752.

257821457 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 255232576 + 2588881 = 15976^2 + 1609^2 .

It is a cyclic number.

It is not a de Polignac number, because 257821457 - 2² = 257821453 is a prime.

It is not a weakly prime, because it can be changed into another prime (257821453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128910728 + 128910729.

It is an arithmetic number, because the mean of its divisors is an integer number (128910729).

Almost surely, 2^257821457 is an apocalyptic number.

It is an amenable number.

257821457 is a deficient number, since it is larger than the sum of its proper divisors (1).

257821457 is an equidigital number, since it uses as much as digits as its factorization.

257821457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 156800, while the sum is 41.

The square root of 257821457 is about 16056.8196415106. The cubic root of 257821457 is about 636.4627917644.

The spelling of 257821457 in words is "two hundred fifty-seven million, eight hundred twenty-one thousand, four hundred fifty-seven".