638555 has 4 divisors (see below), whose sum is σ = 766272. Its totient is φ = 510840.

The previous prime is 638527. The next prime is 638567. The reversal of 638555 is 555836.

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

It is not a de Polignac number, because 638555 - 2¹⁰ = 637531 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 63851 + ... + 63860.

It is an arithmetic number, because the mean of its divisors is an integer number (191568).

2⁶³⁸⁵⁵⁵ is an apocalyptic number.

638555 is a deficient number, since it is larger than the sum of its proper divisors (127717).

638555 is a wasteful number, since it uses less digits than its factorization.

638555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127716.

The product of its digits is 18000, while the sum is 32.

The square root of 638555 is about 799.0963646520. The cubic root of 638555 is about 86.1124812670.

The spelling of 638555 in words is "six hundred thirty-eight thousand, five hundred fifty-five".