71990408538 has 48 divisors (see below), whose sum is σ = 166206516840. Its totient is φ = 22441356288.

The previous prime is 71990408531. The next prime is 71990408557. The reversal of 71990408538 is 83580409917.

71990408538 is a `hidden beast` number, since 7 + 19 + 90 + 4 + 0 + 8 + 538 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 57155899329 + 14834509209 = 239073^2 + 121797^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (71990408531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 701203 + ... + 797286.

Almost surely, 2^71990408538 is an apocalyptic number.

71990408538 is an abundant number, since it is smaller than the sum of its proper divisors (94216108302).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

71990408538 is a wasteful number, since it uses less digits than its factorization.

71990408538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1498671 (or 1498668 counting only the distinct ones).

The product of its (nonzero) digits is 2177280, while the sum is 54.

The spelling of 71990408538 in words is "seventy-one billion, nine hundred ninety million, four hundred eight thousand, five hundred thirty-eight".