638638 has 48 divisors (see below), whose sum is σ = 1340640. Its totient is φ = 221760.

The previous prime is 638633. The next prime is 638663. The reversal of 638638 is 836836.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638633) by changing a digit.

638638 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 (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22008 + ... + 22036.

It is an arithmetic number, because the mean of its divisors is an integer number (27930).

2⁶³⁸⁶³⁸ is an apocalyptic number.

638638 is an abundant number, since it is smaller than the sum of its proper divisors (702002).

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

638638 is a wasteful number, since it uses less digits than its factorization.

638638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73 (or 62 counting only the distinct ones).

The product of its digits is 20736, while the sum is 34.

The square root of 638638 is about 799.1482966259. The cubic root of 638638 is about 86.1162121000.

The spelling of 638638 in words is "six hundred thirty-eight thousand, six hundred thirty-eight".