638878 has 4 divisors (see below), whose sum is σ = 958320. Its totient is φ = 319438.

The previous prime is 638861. The next prime is 638893. The reversal of 638878 is 878836.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 638878.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159718 + ... + 159721.

It is an arithmetic number, because the mean of its divisors is an integer number (239580).

2⁶³⁸⁸⁷⁸ is an apocalyptic number.

638878 is a deficient number, since it is larger than the sum of its proper divisors (319442).

638878 is a wasteful number, since it uses less digits than its factorization.

638878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319441.

The product of its digits is 64512, while the sum is 40.

The square root of 638878 is about 799.2984423856. The cubic root of 638878 is about 86.1269982326.

The spelling of 638878 in words is "six hundred thirty-eight thousand, eight hundred seventy-eight".