638238815 has 16 divisors (see below), whose sum is σ = 795290400. Its totient is φ = 491121792.

The previous prime is 638238787. The next prime is 638238857. The reversal of 638238815 is 518832836.

It is a cyclic number.

It is not a de Polignac number, because 638238815 - 2⁶ = 638238751 is a prime.

It is a congruent number.

It is an unprimeable number.

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, 30824 + ... + 47186.

It is an arithmetic number, because the mean of its divisors is an integer number (49705650).

Almost surely, 2^638238815 is an apocalyptic number.

638238815 is a deficient number, since it is larger than the sum of its proper divisors (157051585).

638238815 is a wasteful number, since it uses less digits than its factorization.

638238815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16666.

The product of its digits is 276480, while the sum is 44.

The square root of 638238815 is about 25263.3888265213. The cubic root of 638238815 is about 860.9826585349.

The spelling of 638238815 in words is "six hundred thirty-eight million, two hundred thirty-eight thousand, eight hundred fifteen".