638855 has 8 divisors (see below), whose sum is σ = 876192. Its totient is φ = 438048.

The previous prime is 638839. The next prime is 638857. The reversal of 638855 is 558836.

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

It is a cyclic number.

It is not a de Polignac number, because 638855 - 2⁴ = 638839 is a prime.

It is a super-2 number, since 2×638855² = 816271422050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (35), and also a Moran number because the ratio is a prime number: 18253 = 638855 / (6 + 3 + 8 + 8 + 5 + 5).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9092 + ... + 9161.

It is an arithmetic number, because the mean of its divisors is an integer number (109524).

2⁶³⁸⁸⁵⁵ is an apocalyptic number.

638855 is a deficient number, since it is larger than the sum of its proper divisors (237337).

638855 is a wasteful number, since it uses less digits than its factorization.

638855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18265.

The product of its digits is 28800, while the sum is 35.

The square root of 638855 is about 799.2840546389. The cubic root of 638855 is about 86.1259646786.

It can be divided in two parts, 638 and 855, that multiplied together give a triangular number (545490 = T₁₀₄₄).

The spelling of 638855 in words is "six hundred thirty-eight thousand, eight hundred fifty-five".