638404 has 12 divisors (see below), whose sum is σ = 1203244. Its totient is φ = 294624.

The previous prime is 638371. The next prime is 638423. The reversal of 638404 is 404836.

It can be written as a sum of positive squares in 2 ways, for example, as 72900 + 565504 = 270^2 + 752^2 .

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

638404 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6087 + ... + 6190.

2⁶³⁸⁴⁰⁴ is an apocalyptic number.

It is an amenable number.

638404 is a deficient number, since it is larger than the sum of its proper divisors (564840).

638404 is a wasteful number, since it uses less digits than its factorization.

638404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12294 (or 12292 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 638404 is about 799.0018773445. The cubic root of 638404 is about 86.1056930186.

It can be divided in two parts, 638 and 404, that multiplied together give a palindrome (257752).

The spelling of 638404 in words is "six hundred thirty-eight thousand, four hundred four".