638634 has 16 divisors (see below), whose sum is σ = 1287072. Its totient is φ = 211248.

The previous prime is 638633. The next prime is 638663. The reversal of 638634 is 436836.

It is an Ulam number.

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

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 652 + ... + 1304.

It is an arithmetic number, because the mean of its divisors is an integer number (80442).

2⁶³⁸⁶³⁴ is an apocalyptic number.

638634 is an abundant number, since it is smaller than the sum of its proper divisors (648438).

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

638634 is a wasteful number, since it uses less digits than its factorization.

638634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 821.

The product of its digits is 10368, while the sum is 30.

The square root of 638634 is about 799.1457939575. The cubic root of 638634 is about 86.1160323083.

The spelling of 638634 in words is "six hundred thirty-eight thousand, six hundred thirty-four".