81091465806413 has 2 divisors, whose sum is σ = 81091465806414. Its totient is φ = 81091465806412.

The previous prime is 81091465806367. The next prime is 81091465806443. The reversal of 81091465806413 is 31460856419018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76249168733929 + 4842297072484 = 8732077^2 + 2200522^2 .

It is a cyclic number.

It is not a de Polignac number, because 81091465806413 - 2¹⁶ = 81091465740877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81091465806443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40545732903206 + 40545732903207.

It is an arithmetic number, because the mean of its divisors is an integer number (40545732903207).

Almost surely, 2^{81091465806413} is an apocalyptic number.

It is an amenable number.

81091465806413 is a deficient number, since it is larger than the sum of its proper divisors (1).

81091465806413 is an equidigital number, since it uses as much as digits as its factorization.

81091465806413 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4976640, while the sum is 56.

The spelling of 81091465806413 in words is "eighty-one trillion, ninety-one billion, four hundred sixty-five million, eight hundred six thousand, four hundred thirteen".