638628155 has 16 divisors (see below), whose sum is σ = 841644000. Its totient is φ = 461333760.

The previous prime is 638628149. The next prime is 638628157. The reversal of 638628155 is 551826836.

638628155 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 638628155 - 2⁴ = 638628139 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638628157) 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, 30770 + ... + 47159.

It is an arithmetic number, because the mean of its divisors is an integer number (52602750).

Almost surely, 2^638628155 is an apocalyptic number.

638628155 is a deficient number, since it is larger than the sum of its proper divisors (203015845).

638628155 is a wasteful number, since it uses less digits than its factorization.

638628155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78094.

The product of its digits is 345600, while the sum is 44.

The square root of 638628155 is about 25271.0932687923. The cubic root of 638628155 is about 861.1576958619.

The spelling of 638628155 in words is "six hundred thirty-eight million, six hundred twenty-eight thousand, one hundred fifty-five".