638805 has 16 divisors (see below), whose sum is σ = 1050624. Its totient is φ = 331200.

The previous prime is 638801. The next prime is 638819. The reversal of 638805 is 508836.

It is not a de Polignac number, because 638805 - 2² = 638801 is a prime.

It is an Ulam number.

It is a nialpdrome in base 15.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 638805.

It is not an unprimeable number, because it can be changed into a prime (638801) 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 15 ways as a sum of consecutive naturals, for example, 21 + ... + 1130.

It is an arithmetic number, because the mean of its divisors is an integer number (65664).

2⁶³⁸⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

638805 is a deficient number, since it is larger than the sum of its proper divisors (411819).

638805 is a wasteful number, since it uses less digits than its factorization.

638805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1196.

The product of its (nonzero) digits is 5760, while the sum is 30.

The square root of 638805 is about 799.2527760352. The cubic root of 638805 is about 86.1237177365.

The spelling of 638805 in words is "six hundred thirty-eight thousand, eight hundred five".