638944 has 24 divisors (see below), whose sum is σ = 1291248. Its totient is φ = 311040.

The previous prime is 638933. The next prime is 638959. The reversal of 638944 is 449836.

It is a Smith number, since the sum of its digits (34) coincides with the sum of the digits of its prime factors.

It is a plaindrome in base 14.

It is a congruent number.

It is an unprimeable number.

638944 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1069 + ... + 1555.

It is an arithmetic number, because the mean of its divisors is an integer number (53802).

638944 is a Friedman number, since it can be written as (39*4^6-8)*4, using all its digits and the basic arithmetic operations.

2⁶³⁸⁹⁴⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (645624).

638944 is an abundant number, since it is smaller than the sum of its proper divisors (652304).

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

638944 is a wasteful number, since it uses less digits than its factorization.

638944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 538 (or 530 counting only the distinct ones).

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

The square root of 638944 is about 799.3397275252. The cubic root of 638944 is about 86.1299639455.

The spelling of 638944 in words is "six hundred thirty-eight thousand, nine hundred forty-four".