638565 has 8 divisors (see below), whose sum is σ = 1021728. Its totient is φ = 340560.

The previous prime is 638527. The next prime is 638567. The reversal of 638565 is 565836.

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

It is not a de Polignac number, because 638565 - 2⁶ = 638501 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638567) 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, 21271 + ... + 21300.

It is an arithmetic number, because the mean of its divisors is an integer number (127716).

2⁶³⁸⁵⁶⁵ is an apocalyptic number.

It is an amenable number.

638565 is a deficient number, since it is larger than the sum of its proper divisors (383163).

638565 is a wasteful number, since it uses less digits than its factorization.

638565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42579.

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

The square root of 638565 is about 799.1026216951. The cubic root of 638565 is about 86.1129307821.

The spelling of 638565 in words is "six hundred thirty-eight thousand, five hundred sixty-five".