638505 has 24 divisors (see below), whose sum is σ = 1265472. Its totient is φ = 291744.

The previous prime is 638501. The next prime is 638527. The reversal of 638505 is 505836.

It is not a de Polignac number, because 638505 - 2² = 638501 is a prime.

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (638501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 699 + ... + 1328.

It is an arithmetic number, because the mean of its divisors is an integer number (52728).

2⁶³⁸⁵⁰⁵ is an apocalyptic number.

It is an amenable number.

638505 is a deficient number, since it is larger than the sum of its proper divisors (626967).

638505 is a wasteful number, since it uses less digits than its factorization.

638505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2045 (or 2042 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 638505 is about 799.0650787014. The cubic root of 638505 is about 86.1102336212.

The spelling of 638505 in words is "six hundred thirty-eight thousand, five hundred five".