638831 has 4 divisors (see below), whose sum is σ = 643632. Its totient is φ = 634032.

The previous prime is 638819. The next prime is 638839. The reversal of 638831 is 138836.

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

It is a cyclic number.

It is not a de Polignac number, because 638831 - 2⁶ = 638767 is a prime.

It is a super-2 number, since 2×638831² = 816210093122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 638794 and 638803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638839) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2195 + ... + 2468.

It is an arithmetic number, because the mean of its divisors is an integer number (160908).

2⁶³⁸⁸³¹ is an apocalyptic number.

638831 is a deficient number, since it is larger than the sum of its proper divisors (4801).

638831 is a wasteful number, since it uses less digits than its factorization.

638831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4800.

The product of its digits is 3456, while the sum is 29.

The square root of 638831 is about 799.2690410619. The cubic root of 638831 is about 86.1248861611.

The spelling of 638831 in words is "six hundred thirty-eight thousand, eight hundred thirty-one".