638440 has 32 divisors (see below), whose sum is σ = 1568160. Its totient is φ = 232000.

The previous prime is 638437. The next prime is 638453. The reversal of 638440 is 44836.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 286 + ... + 1165.

It is an arithmetic number, because the mean of its divisors is an integer number (49005).

2⁶³⁸⁴⁴⁰ is an apocalyptic number.

It is an amenable number.

638440 is an abundant number, since it is smaller than the sum of its proper divisors (929720).

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

638440 is a wasteful number, since it uses less digits than its factorization.

638440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1473 (or 1469 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 638440 is about 799.0244051342. The cubic root of 638440 is about 86.1073115061.

The spelling of 638440 in words is "six hundred thirty-eight thousand, four hundred forty".