81131708528444 has 48 divisors (see below), whose sum is σ = 162525826068480. Its totient is φ = 34714528914240.

The previous prime is 81131708528417. The next prime is 81131708528503. The reversal of 81131708528444 is 44482580713118.

It is a super-2 number, since 2×81131708528444² (a number of 29 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81131708528444.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 71311247 + ... + 72440025.

It is an arithmetic number, because the mean of its divisors is an integer number (3385954709760).

Almost surely, 2^{81131708528444} is an apocalyptic number.

It is an amenable number.

81131708528444 is an abundant number, since it is smaller than the sum of its proper divisors (81394117540036).

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

81131708528444 is a wasteful number, since it uses less digits than its factorization.

81131708528444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1132938 (or 1132936 counting only the distinct ones).

The product of its (nonzero) digits is 6881280, while the sum is 56.

The spelling of 81131708528444 in words is "eighty-one trillion, one hundred thirty-one billion, seven hundred eight million, five hundred twenty-eight thousand, four hundred forty-four".