257638397 has 2 divisors, whose sum is σ = 257638398. Its totient is φ = 257638396.

The previous prime is 257638393. The next prime is 257638421. The reversal of 257638397 is 793836752.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 229643716 + 27994681 = 15154^2 + 5291^2 .

It is a cyclic number.

It is not a de Polignac number, because 257638397 - 2² = 257638393 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257638393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128819198 + 128819199.

It is an arithmetic number, because the mean of its divisors is an integer number (128819199).

Almost surely, 2^257638397 is an apocalyptic number.

It is an amenable number.

257638397 is a deficient number, since it is larger than the sum of its proper divisors (1).

257638397 is an equidigital number, since it uses as much as digits as its factorization.

257638397 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1905120, while the sum is 50.

The square root of 257638397 is about 16051.1182476487. The cubic root of 257638397 is about 636.3121210042.

The spelling of 257638397 in words is "two hundred fifty-seven million, six hundred thirty-eight thousand, three hundred ninety-seven".