81664111 has 2 divisors, whose sum is σ = 81664112. Its totient is φ = 81664110.

The previous prime is 81664067. The next prime is 81664127. The reversal of 81664111 is 11146618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81664111 - 2⁷ = 81663983 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81664111.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81664171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40832055 + 40832056.

It is an arithmetic number, because the mean of its divisors is an integer number (40832056).

Almost surely, 2^81664111 is an apocalyptic number.

81664111 is a deficient number, since it is larger than the sum of its proper divisors (1).

81664111 is an equidigital number, since it uses as much as digits as its factorization.

81664111 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 28.

The square root of 81664111 is about 9036.8197392667. The cubic root of 81664111 is about 433.8541402149.

The spelling of 81664111 in words is "eighty-one million, six hundred sixty-four thousand, one hundred eleven".