81528709955591 has 2 divisors, whose sum is σ = 81528709955592. Its totient is φ = 81528709955590.

The previous prime is 81528709955579. The next prime is 81528709955701. The reversal of 81528709955591 is 19555990782518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81528709955591 - 2²⁶ = 81528642846727 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81528709955531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40764354977795 + 40764354977796.

It is an arithmetic number, because the mean of its divisors is an integer number (40764354977796).

Almost surely, 2^{81528709955591} is an apocalyptic number.

81528709955591 is a deficient number, since it is larger than the sum of its proper divisors (1).

81528709955591 is an equidigital number, since it uses as much as digits as its factorization.

81528709955591 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 408240000, while the sum is 74.

The spelling of 81528709955591 in words is "eighty-one trillion, five hundred twenty-eight billion, seven hundred nine million, nine hundred fifty-five thousand, five hundred ninety-one".