638784655 has 16 divisors (see below), whose sum is σ = 809791200. Its totient is φ = 482388480.

The previous prime is 638784649. The next prime is 638784659. The reversal of 638784655 is 556487836.

It is not a de Polignac number, because 638784655 - 2⁵ = 638784623 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638784659) 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 15 ways as a sum of consecutive naturals, for example, 14731 + ... + 38659.

It is an arithmetic number, because the mean of its divisors is an integer number (50611950).

Almost surely, 2^638784655 is an apocalyptic number.

638784655 is a deficient number, since it is larger than the sum of its proper divisors (171006545).

638784655 is a wasteful number, since it uses less digits than its factorization.

638784655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24234.

The product of its digits is 4838400, while the sum is 52.

The square root of 638784655 is about 25274.1895023362. The cubic root of 638784655 is about 861.2280342223.

The spelling of 638784655 in words is "six hundred thirty-eight million, seven hundred eighty-four thousand, six hundred fifty-five".