81211711723 has 16 divisors (see below), whose sum is σ = 86161766400. Its totient is φ = 76331626560.

The previous prime is 81211711709. The next prime is 81211711733. The reversal of 81211711723 is 32711711218.

It is a cyclic number.

It is not a de Polignac number, because 81211711723 - 2²¹ = 81209614571 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81211711733) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1197615 + ... + 1263607.

It is an arithmetic number, because the mean of its divisors is an integer number (5385110400).

Almost surely, 2^81211711723 is an apocalyptic number.

81211711723 is a deficient number, since it is larger than the sum of its proper divisors (4950054677).

81211711723 is a wasteful number, since it uses less digits than its factorization.

81211711723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66522.

The product of its digits is 4704, while the sum is 34.

The spelling of 81211711723 in words is "eighty-one billion, two hundred eleven million, seven hundred eleven thousand, seven hundred twenty-three".