638405136185 has 16 divisors (see below), whose sum is σ = 817070873616. Its totient is φ = 477172881408.

The previous prime is 638405136181. The next prime is 638405136203. The reversal of 638405136185 is 581631504836.

It can be written as a sum of positive squares in 8 ways, for example, as 113827963456 + 524577172729 = 337384^2 + 724277^2 .

It is not a de Polignac number, because 638405136185 - 2² = 638405136181 is a prime.

It is a super-2 number, since 2×638405136185² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638405136181) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27399482 + ... + 27422771.

It is an arithmetic number, because the mean of its divisors is an integer number (51066929601).

Almost surely, 2^638405136185 is an apocalyptic number.

It is an amenable number.

638405136185 is a deficient number, since it is larger than the sum of its proper divisors (178665737431).

638405136185 is a wasteful number, since it uses less digits than its factorization.

638405136185 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54822412.

The product of its (nonzero) digits is 2073600, while the sum is 50.

It can be divided in two parts, 63840 and 5136185, that added together give a palindrome (5200025).

The spelling of 638405136185 in words is "six hundred thirty-eight billion, four hundred five million, one hundred thirty-six thousand, one hundred eighty-five".