638865 has 12 divisors (see below), whose sum is σ = 1107444. Its totient is φ = 340704.

The previous prime is 638861. The next prime is 638893. The reversal of 638865 is 568836.

It can be written as a sum of positive squares in 2 ways, for example, as 484416 + 154449 = 696^2 + 393^2 .

It is not a de Polignac number, because 638865 - 2² = 638861 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638861) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7054 + ... + 7143.

It is an arithmetic number, because the mean of its divisors is an integer number (92287).

2⁶³⁸⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

638865 is a deficient number, since it is larger than the sum of its proper divisors (468579).

638865 is a wasteful number, since it uses less digits than its factorization.

638865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14208 (or 14205 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 638865 is about 799.2903102128. The cubic root of 638865 is about 86.1264140530.

The spelling of 638865 in words is "six hundred thirty-eight thousand, eight hundred sixty-five".