81115731211 has 2 divisors, whose sum is σ = 81115731212. Its totient is φ = 81115731210.

The previous prime is 81115731197. The next prime is 81115731241. The reversal of 81115731211 is 11213751118.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81115731211 - 2⁷ = 81115731083 is a prime.

It is not a weakly prime, because it can be changed into another prime (81115731241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40557865605 + 40557865606.

It is an arithmetic number, because the mean of its divisors is an integer number (40557865606).

Almost surely, 2^81115731211 is an apocalyptic number.

81115731211 is a deficient number, since it is larger than the sum of its proper divisors (1).

81115731211 is an equidigital number, since it uses as much as digits as its factorization.

81115731211 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1680, while the sum is 31.

The spelling of 81115731211 in words is "eighty-one billion, one hundred fifteen million, seven hundred thirty-one thousand, two hundred eleven".