257642221 has 2 divisors, whose sum is σ = 257642222. Its totient is φ = 257642220.

The previous prime is 257642219. The next prime is 257642263. The reversal of 257642221 is 122246752.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 159037321 + 98604900 = 12611^2 + 9930^2 .

It is a cyclic number.

It is not a de Polignac number, because 257642221 - 2¹ = 257642219 is a prime.

Together with 257642219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257642291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128821110 + 128821111.

It is an arithmetic number, because the mean of its divisors is an integer number (128821111).

Almost surely, 2^257642221 is an apocalyptic number.

It is an amenable number.

257642221 is a deficient number, since it is larger than the sum of its proper divisors (1).

257642221 is an equidigital number, since it uses as much as digits as its factorization.

257642221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13440, while the sum is 31.

The square root of 257642221 is about 16051.2373666331. The cubic root of 257642221 is about 636.3152691446.

Adding to 257642221 its reverse (122246752), we get a palindrome (379888973).

The spelling of 257642221 in words is "two hundred fifty-seven million, six hundred forty-two thousand, two hundred twenty-one".