638569 has 4 divisors (see below), whose sum is σ = 659200. Its totient is φ = 617940.

The previous prime is 638567. The next prime is 638581. The reversal of 638569 is 965836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 638569 - 2¹ = 638567 is a prime.

It is a super-2 number, since 2×638569² = 815540735522, which contains 22 as substring.

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

It is a Duffinian 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 3 ways as a sum of consecutive naturals, for example, 10269 + ... + 10330.

It is an arithmetic number, because the mean of its divisors is an integer number (164800).

2⁶³⁸⁵⁶⁹ is an apocalyptic number.

It is an amenable number.

638569 is a deficient number, since it is larger than the sum of its proper divisors (20631).

638569 is a wasteful number, since it uses less digits than its factorization.

638569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20630.

The product of its digits is 38880, while the sum is 37.

The square root of 638569 is about 799.1051244986. The cubic root of 638569 is about 86.1131105868.

The spelling of 638569 in words is "six hundred thirty-eight thousand, five hundred sixty-nine".