81079891792 has 20 divisors (see below), whose sum is σ = 157146606036. Its totient is φ = 40525928960.

The previous prime is 81079891769. The next prime is 81079891793. The reversal of 81079891792 is 29719897018.

It can be written as a sum of positive squares in 2 ways, for example, as 30546650176 + 50533241616 = 174776^2 + 224796^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81079891792.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81079891793) 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 3 ways as a sum of consecutive naturals, for example, 828259 + ... + 920962.

Almost surely, 2^81079891792 is an apocalyptic number.

It is an amenable number.

81079891792 is a deficient number, since it is larger than the sum of its proper divisors (76066714244).

81079891792 is a wasteful number, since it uses less digits than its factorization.

81079891792 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1752126 (or 1752120 counting only the distinct ones).

The product of its (nonzero) digits is 4572288, while the sum is 61.

The spelling of 81079891792 in words is "eighty-one billion, seventy-nine million, eight hundred ninety-one thousand, seven hundred ninety-two".