638745 has 16 divisors (see below), whose sum is σ = 1034880. Its totient is φ = 336384.

The previous prime is 638719. The next prime is 638767. The reversal of 638745 is 547836.

It is not a de Polignac number, because 638745 - 2⁸ = 638489 is a prime.

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

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1236 + ... + 1674.

It is an arithmetic number, because the mean of its divisors is an integer number (64680).

2⁶³⁸⁷⁴⁵ is an apocalyptic number.

It is an amenable number.

638745 is a deficient number, since it is larger than the sum of its proper divisors (396135).

638745 is a wasteful number, since it uses less digits than its factorization.

638745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 544.

The product of its digits is 20160, while the sum is 33.

The square root of 638745 is about 799.2152400949. The cubic root of 638745 is about 86.1210212512.

Subtracting from 638745 its reverse (547836), we obtain a palindrome (90909).

The spelling of 638745 in words is "six hundred thirty-eight thousand, seven hundred forty-five".