81609656111 has 2 divisors, whose sum is σ = 81609656112. Its totient is φ = 81609656110.

The previous prime is 81609656099. The next prime is 81609656113. The reversal of 81609656111 is 11165690618.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81609656111 is a prime.

Together with 81609656113, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81609656113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40804828055 + 40804828056.

It is an arithmetic number, because the mean of its divisors is an integer number (40804828056).

Almost surely, 2^81609656111 is an apocalyptic number.

81609656111 is a deficient number, since it is larger than the sum of its proper divisors (1).

81609656111 is an equidigital number, since it uses as much as digits as its factorization.

81609656111 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 77760, while the sum is 44.

The spelling of 81609656111 in words is "eighty-one billion, six hundred nine million, six hundred fifty-six thousand, one hundred eleven".