638644678 has 16 divisors (see below), whose sum is σ = 1159221024. Its totient is φ = 257604480.

The previous prime is 638644673. The next prime is 638644681. The reversal of 638644678 is 876446836.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638644673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1341453 + ... + 1341928.

It is an arithmetic number, because the mean of its divisors is an integer number (72451314).

Almost surely, 2^638644678 is an apocalyptic number.

638644678 is a deficient number, since it is larger than the sum of its proper divisors (520576346).

638644678 is a wasteful number, since it uses less digits than its factorization.

638644678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2683407.

The product of its digits is 4644864, while the sum is 52.

The square root of 638644678 is about 25271.4201816993. The cubic root of 638644678 is about 861.1651226072.

The spelling of 638644678 in words is "six hundred thirty-eight million, six hundred forty-four thousand, six hundred seventy-eight".