81724443541 has 6 divisors (see below), whose sum is σ = 88494515970. Its totient is φ = 75437947728.

The previous prime is 81724443539. The next prime is 81724443613. The reversal of 81724443541 is 14534442718.

It can be written as a sum of positive squares in 3 ways, for example, as 6291821041 + 75432622500 = 79321^2 + 274650^2 .

It is not a de Polignac number, because 81724443541 - 2¹ = 81724443539 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81724441541) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 241788126 + ... + 241788463.

It is an arithmetic number, because the mean of its divisors is an integer number (14749085995).

Almost surely, 2^81724443541 is an apocalyptic number.

It is an amenable number.

81724443541 is a deficient number, since it is larger than the sum of its proper divisors (6770072429).

81724443541 is a wasteful number, since it uses less digits than its factorization.

81724443541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 483576615 (or 483576602 counting only the distinct ones).

The product of its digits is 430080, while the sum is 43.

The spelling of 81724443541 in words is "eighty-one billion, seven hundred twenty-four million, four hundred forty-three thousand, five hundred forty-one".