81211117611 has 32 divisors (see below), whose sum is σ = 123497095680. Its totient is φ = 47089684224.

The previous prime is 81211117609. The next prime is 81211117619. The reversal of 81211117611 is 11671111218.

It is not a de Polignac number, because 81211117611 - 2¹ = 81211117609 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81211117619) 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 31 ways as a sum of consecutive naturals, for example, 615546 + ... + 735743.

It is an arithmetic number, because the mean of its divisors is an integer number (3859284240).

Almost surely, 2^81211117611 is an apocalyptic number.

81211117611 is a deficient number, since it is larger than the sum of its proper divisors (42285978069).

81211117611 is a wasteful number, since it uses less digits than its factorization.

81211117611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1351395.

The product of its digits is 672, while the sum is 30.

Adding to 81211117611 its reverse (11671111218), we get a palindrome (92882228829).

The spelling of 81211117611 in words is "eighty-one billion, two hundred eleven million, one hundred seventeen thousand, six hundred eleven".