71531387920 has 20 divisors (see below), whose sum is σ = 166310477100. Its totient is φ = 28612555136.

The previous prime is 71531387909. The next prime is 71531388001. The reversal of 71531387920 is 2978313517.

It can be written as a sum of positive squares in 2 ways, for example, as 40429949184 + 31101438736 = 201072^2 + 176356^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 447071095 + ... + 447071254.

It is an arithmetic number, because the mean of its divisors is an integer number (8315523855).

Almost surely, 2^71531387920 is an apocalyptic number.

It is an amenable number.

71531387920 is an abundant number, since it is smaller than the sum of its proper divisors (94779089180).

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

71531387920 is a wasteful number, since it uses less digits than its factorization.

71531387920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 894142362 (or 894142356 counting only the distinct ones).

The product of its (nonzero) digits is 317520, while the sum is 46.

The spelling of 71531387920 in words is "seventy-one billion, five hundred thirty-one million, three hundred eighty-seven thousand, nine hundred twenty".