638605 has 16 divisors (see below), whose sum is σ = 886464. Its totient is φ = 436480.

The previous prime is 638587. The next prime is 638621. The reversal of 638605 is 506836.

It is not a de Polignac number, because 638605 - 2¹⁵ = 605837 is a prime.

It is a Duffinian number.

638605 is a lucky number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 594 + ... + 1276.

It is an arithmetic number, because the mean of its divisors is an integer number (55404).

2⁶³⁸⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

638605 is a deficient number, since it is larger than the sum of its proper divisors (247859).

638605 is a wasteful number, since it uses less digits than its factorization.

638605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 716.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 638605 is about 799.1276493777. The cubic root of 638605 is about 86.1147287955.

Subtracting from 638605 its reverse (506836), we obtain a square (131769 = 363²).

It can be divided in two parts, 63 and 8605, that added together give a palindrome (8668).

The spelling of 638605 in words is "six hundred thirty-eight thousand, six hundred five".