81439684335791 has 2 divisors, whose sum is σ = 81439684335792. Its totient is φ = 81439684335790.

The previous prime is 81439684335733. The next prime is 81439684335799. The reversal of 81439684335791 is 19753348693418.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81439684335791 - 2⁶ = 81439684335727 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81439684335799) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40719842167895 + 40719842167896.

It is an arithmetic number, because the mean of its divisors is an integer number (40719842167896).

Almost surely, 2^{81439684335791} is an apocalyptic number.

81439684335791 is a deficient number, since it is larger than the sum of its proper divisors (1).

81439684335791 is an equidigital number, since it uses as much as digits as its factorization.

81439684335791 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 470292480, while the sum is 71.

The spelling of 81439684335791 in words is "eighty-one trillion, four hundred thirty-nine billion, six hundred eighty-four million, three hundred thirty-five thousand, seven hundred ninety-one".