638625855 has 16 divisors (see below), whose sum is σ = 1167773184. Its totient is φ = 291943200.

The previous prime is 638625851. The next prime is 638625857. The reversal of 638625855 is 558526836.

It is not a de Polignac number, because 638625855 - 2² = 638625851 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638625851) 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, 3040971 + ... + 3041180.

It is an arithmetic number, because the mean of its divisors is an integer number (72985824).

Almost surely, 2^638625855 is an apocalyptic number.

638625855 is a deficient number, since it is larger than the sum of its proper divisors (529147329).

638625855 is a wasteful number, since it uses less digits than its factorization.

638625855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6082166.

The product of its digits is 1728000, while the sum is 48.

The square root of 638625855 is about 25271.0477622120. The cubic root of 638625855 is about 861.1566620495.

The spelling of 638625855 in words is "six hundred thirty-eight million, six hundred twenty-five thousand, eight hundred fifty-five".