638655 has 8 divisors (see below), whose sum is σ = 1021872. Its totient is φ = 340608.

The previous prime is 638633. The next prime is 638663. The reversal of 638655 is 556836.

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

It is not a de Polignac number, because 638655 - 2⁷ = 638527 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21274 + ... + 21303.

It is an arithmetic number, because the mean of its divisors is an integer number (127734).

2⁶³⁸⁶⁵⁵ is an apocalyptic number.

638655 is a deficient number, since it is larger than the sum of its proper divisors (383217).

638655 is a wasteful number, since it uses less digits than its factorization.

638655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42585.

The product of its digits is 21600, while the sum is 33.

The square root of 638655 is about 799.1589328788. The cubic root of 638655 is about 86.1169762067.

It can be divided in two parts, 6386 and 55, that added together give a triangular number (6441 = T₁₁₃).

The spelling of 638655 in words is "six hundred thirty-eight thousand, six hundred fifty-five".