257385781 has 2 divisors, whose sum is σ = 257385782. Its totient is φ = 257385780.

The previous prime is 257385743. The next prime is 257385803. The reversal of 257385781 is 187583752.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 244640881 + 12744900 = 15641^2 + 3570^2 .

It is a cyclic number.

It is not a de Polignac number, because 257385781 - 2¹⁵ = 257353013 is a prime.

It is a super-2 number, since 2×257385781² = 132494880521959922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257385731) 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, 128692890 + 128692891.

It is an arithmetic number, because the mean of its divisors is an integer number (128692891).

Almost surely, 2^257385781 is an apocalyptic number.

It is an amenable number.

257385781 is a deficient number, since it is larger than the sum of its proper divisors (1).

257385781 is an equidigital number, since it uses as much as digits as its factorization.

257385781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 470400, while the sum is 46.

The square root of 257385781 is about 16043.2472087168. The cubic root of 257385781 is about 636.1040837064.

The spelling of 257385781 in words is "two hundred fifty-seven million, three hundred eighty-five thousand, seven hundred eighty-one".