81579699811 has 4 divisors (see below), whose sum is σ = 81929827512. Its totient is φ = 81229572112.

The previous prime is 81579699769. The next prime is 81579699821. The reversal of 81579699811 is 11899697518.

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 81579699811 - 2⁷ = 81579699683 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81579699821) 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, 175063501 + ... + 175063966.

It is an arithmetic number, because the mean of its divisors is an integer number (20482456878).

Almost surely, 2^81579699811 is an apocalyptic number.

81579699811 is a deficient number, since it is larger than the sum of its proper divisors (350127701).

81579699811 is a wasteful number, since it uses less digits than its factorization.

81579699811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350127700.

The product of its digits is 9797760, while the sum is 64.

The spelling of 81579699811 in words is "eighty-one billion, five hundred seventy-nine million, six hundred ninety-nine thousand, eight hundred eleven".