81091465806399 has 16 divisors (see below), whose sum is σ = 108429832158720. Its totient is φ = 53907074383680.

The previous prime is 81091465806367. The next prime is 81091465806413. The reversal of 81091465806399 is 99360856419018.

It is a Cunningham number, because it is equal to 9005080²-1.

It is not a de Polignac number, because 81091465806399 - 2⁵ = 81091465806367 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81091465806599) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4502539 + ... + 13507619.

It is an arithmetic number, because the mean of its divisors is an integer number (6776864509920).

Almost surely, 2^{81091465806399} is an apocalyptic number.

81091465806399 is a deficient number, since it is larger than the sum of its proper divisors (27338366352321).

81091465806399 is a wasteful number, since it uses less digits than its factorization.

81091465806399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9013630.

The product of its (nonzero) digits is 100776960, while the sum is 69.

The spelling of 81091465806399 in words is "eighty-one trillion, ninety-one billion, four hundred sixty-five million, eight hundred six thousand, three hundred ninety-nine".