638688105 has 32 divisors (see below), whose sum is σ = 1238670720. Its totient is φ = 309666240.

The previous prime is 638688103. The next prime is 638688137. The reversal of 638688105 is 501886836.

638688105 is a `hidden beast` number, since 638 + 6 + 8 + 8 + 1 + 0 + 5 = 666.

It is not a de Polignac number, because 638688105 - 2¹ = 638688103 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (638688101) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 213562 + ... + 216531.

It is an arithmetic number, because the mean of its divisors is an integer number (38708460).

Almost surely, 2^638688105 is an apocalyptic number.

It is an amenable number.

638688105 is a deficient number, since it is larger than the sum of its proper divisors (599982615).

638688105 is a wasteful number, since it uses less digits than its factorization.

638688105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430118 (or 430112 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The square root of 638688105 is about 25272.2793787976. The cubic root of 638688105 is about 861.1846415308.

The spelling of 638688105 in words is "six hundred thirty-eight million, six hundred eighty-eight thousand, one hundred five".