81720865580292 has 48 divisors (see below), whose sum is σ = 211869466910080. Its totient is φ = 27240217022304.

The previous prime is 81720865580251. The next prime is 81720865580311. The reversal of 81720865580292 is 29208556802718.

81720865580292 is a `hidden beast` number, since 8 + 1 + 7 + 20 + 8 + 6 + 5 + 580 + 29 + 2 = 666.

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, 54769698 + ... + 56241990.

Almost surely, 2^{81720865580292} is an apocalyptic number.

It is an amenable number.

81720865580292 is an abundant number, since it is smaller than the sum of its proper divisors (130148601329788).

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

81720865580292 is a wasteful number, since it uses less digits than its factorization.

81720865580292 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1986249 (or 1986241 counting only the distinct ones).

The product of its (nonzero) digits is 38707200, while the sum is 63.

The spelling of 81720865580292 in words is "eighty-one trillion, seven hundred twenty billion, eight hundred sixty-five million, five hundred eighty thousand, two hundred ninety-two".