638585 has 4 divisors (see below), whose sum is σ = 766308. Its totient is φ = 510864.

The previous prime is 638581. The next prime is 638587. The reversal of 638585 is 585836.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 434281 + 204304 = 659^2 + 452^2 .

It is a cyclic number.

It is not a de Polignac number, because 638585 - 2² = 638581 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63854 + ... + 63863.

It is an arithmetic number, because the mean of its divisors is an integer number (191577).

2⁶³⁸⁵⁸⁵ is an apocalyptic number.

It is an amenable number.

638585 is a deficient number, since it is larger than the sum of its proper divisors (127723).

638585 is a wasteful number, since it uses less digits than its factorization.

638585 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127722.

The product of its digits is 28800, while the sum is 35.

The square root of 638585 is about 799.1151356344. The cubic root of 638585 is about 86.1138297982.

The spelling of 638585 in words is "six hundred thirty-eight thousand, five hundred eighty-five".