638818 has 8 divisors (see below), whose sum is σ = 1008720. Its totient is φ = 302580.

The previous prime is 638801. The next prime is 638819. The reversal of 638818 is 818836.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (638819) by changing a digit.

638818 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, 8368 + ... + 8443.

It is an arithmetic number, because the mean of its divisors is an integer number (126090).

2⁶³⁸⁸¹⁸ is an apocalyptic number.

638818 is a deficient number, since it is larger than the sum of its proper divisors (369902).

638818 is a wasteful number, since it uses less digits than its factorization.

638818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16832.

The product of its digits is 9216, while the sum is 34.

The square root of 638818 is about 799.2609085899. The cubic root of 638818 is about 86.1243019528.

The spelling of 638818 in words is "six hundred thirty-eight thousand, eight hundred eighteen".