257645749 has 2 divisors, whose sum is σ = 257645750. Its totient is φ = 257645748.

The previous prime is 257645711. The next prime is 257645767. The reversal of 257645749 is 947546752.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 218832849 + 38812900 = 14793^2 + 6230^2 .

It is a cyclic number.

It is not a de Polignac number, because 257645749 - 2¹⁹ = 257121461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257645449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128822874 + 128822875.

It is an arithmetic number, because the mean of its divisors is an integer number (128822875).

Almost surely, 2^257645749 is an apocalyptic number.

It is an amenable number.

257645749 is a deficient number, since it is larger than the sum of its proper divisors (1).

257645749 is an equidigital number, since it uses as much as digits as its factorization.

257645749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2116800, while the sum is 49.

The square root of 257645749 is about 16051.3472643264. The cubic root of 257645749 is about 636.3181735728.

It can be divided in two parts, 25764 and 5749, that added together give a palindrome (31513).

The spelling of 257645749 in words is "two hundred fifty-seven million, six hundred forty-five thousand, seven hundred forty-nine".