638864 has 10 divisors (see below), whose sum is σ = 1237830. Its totient is φ = 319424.

The previous prime is 638861. The next prime is 638893. The reversal of 638864 is 468836.

It can be written as a sum of positive squares in only one way, i.e., 478864 + 160000 = 692^2 + 400^2 .

It is not an unprimeable number, because it can be changed into a prime (638861) 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 as a sum of consecutive naturals, namely, 19949 + ... + 19980.

It is an arithmetic number, because the mean of its divisors is an integer number (123783).

2⁶³⁸⁸⁶⁴ is an apocalyptic number.

It is an amenable number.

638864 is a deficient number, since it is larger than the sum of its proper divisors (598966).

638864 is a wasteful number, since it uses less digits than its factorization.

638864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39937 (or 39931 counting only the distinct ones).

The product of its digits is 27648, while the sum is 35.

The square root of 638864 is about 799.2896846576. The cubic root of 638864 is about 86.1263691158.

The spelling of 638864 in words is "six hundred thirty-eight thousand, eight hundred sixty-four".