638660 has 24 divisors (see below), whose sum is σ = 1463616. Its totient is φ = 232160.

The previous prime is 638633. The next prime is 638663. The reversal of 638660 is 66836.

It is not an unprimeable number, because it can be changed into a prime (638663) by changing a digit.

638660 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 7 ways as a sum of consecutive naturals, for example, 1232 + ... + 1671.

It is an arithmetic number, because the mean of its divisors is an integer number (60984).

2⁶³⁸⁶⁶⁰ is an apocalyptic number.

It is an amenable number.

638660 is an abundant number, since it is smaller than the sum of its proper divisors (824956).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638660 is a wasteful number, since it uses less digits than its factorization.

638660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2923 (or 2921 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 638660 is about 799.1620611616. The cubic root of 638660 is about 86.1172009413.

It can be divided in two parts, 6386 and 60, that added together give a palindrome (6446).

The spelling of 638660 in words is "six hundred thirty-eight thousand, six hundred sixty".