638835 has 8 divisors (see below), whose sum is σ = 1022160. Its totient is φ = 340704.

The previous prime is 638819. The next prime is 638839. The reversal of 638835 is 538836.

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

It is not a de Polignac number, because 638835 - 2⁴ = 638819 is a prime.

It is a super-2 number, since 2×638835² = 816220314450, which contains 22 as substring.

638835 is a lucky number.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 638796 and 638805.

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 7 ways as a sum of consecutive naturals, for example, 21280 + ... + 21309.

It is an arithmetic number, because the mean of its divisors is an integer number (127770).

2⁶³⁸⁸³⁵ is an apocalyptic number.

638835 is a deficient number, since it is larger than the sum of its proper divisors (383325).

638835 is a wasteful number, since it uses less digits than its factorization.

638835 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42597.

The product of its digits is 17280, while the sum is 33.

The square root of 638835 is about 799.2715433443. The cubic root of 638835 is about 86.1250659159.

Subtracting from 638835 its reverse (538836), we obtain a palindrome (99999).

The spelling of 638835 in words is "six hundred thirty-eight thousand, eight hundred thirty-five".