638561 has 8 divisors (see below), whose sum is σ = 796224. Its totient is φ = 497520.

The previous prime is 638527. The next prime is 638567. The reversal of 638561 is 165836.

638561 = 64² + 65² + ... + 129².

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

It is a cyclic number.

It is not a de Polignac number, because 638561 - 2¹⁴ = 622177 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (638567) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 4070 + ... + 4223.

It is an arithmetic number, because the mean of its divisors is an integer number (99528).

2⁶³⁸⁵⁶¹ is an apocalyptic number.

It is an amenable number.

638561 is a deficient number, since it is larger than the sum of its proper divisors (157663).

638561 is a wasteful number, since it uses less digits than its factorization.

638561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8311.

The product of its digits is 4320, while the sum is 29.

The square root of 638561 is about 799.1001188837. The cubic root of 638561 is about 86.1127509766.

It can be divided in two parts, 6385 and 61, that added together give a palindrome (6446).

The spelling of 638561 in words is "six hundred thirty-eight thousand, five hundred sixty-one".