638857 has 2 divisors, whose sum is σ = 638858. Its totient is φ = 638856.

The previous prime is 638839. The next prime is 638861. The reversal of 638857 is 758836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 491401 + 147456 = 701^2 + 384^2 .

It is a cyclic number.

It is not a de Polignac number, because 638857 - 2¹¹ = 636809 is a prime.

It is not a weakly prime, because it can be changed into another prime (632857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319428 + 319429.

It is an arithmetic number, because the mean of its divisors is an integer number (319429).

2⁶³⁸⁸⁵⁷ is an apocalyptic number.

It is an amenable number.

638857 is a deficient number, since it is larger than the sum of its proper divisors (1).

638857 is an equidigital number, since it uses as much as digits as its factorization.

638857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 37.

The square root of 638857 is about 799.2853057576. The cubic root of 638857 is about 86.1260545539.

The spelling of 638857 in words is "six hundred thirty-eight thousand, eight hundred fifty-seven".