81305916811 has 4 divisors (see below), whose sum is σ = 92921047792. Its totient is φ = 69690785832.

The previous prime is 81305916751. The next prime is 81305916883. The reversal of 81305916811 is 11861950318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81305916811 - 2⁷ = 81305916683 is a prime.

It is a super-2 number, since 2×81305916811² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81305911811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5807565480 + ... + 5807565493.

It is an arithmetic number, because the mean of its divisors is an integer number (23230261948).

Almost surely, 2^81305916811 is an apocalyptic number.

81305916811 is a deficient number, since it is larger than the sum of its proper divisors (11615130981).

81305916811 is a wasteful number, since it uses less digits than its factorization.

81305916811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11615130980.

The product of its (nonzero) digits is 51840, while the sum is 43.

The spelling of 81305916811 in words is "eighty-one billion, three hundred five million, nine hundred sixteen thousand, eight hundred eleven".