81528304132861 has 2 divisors, whose sum is σ = 81528304132862. Its totient is φ = 81528304132860.

The previous prime is 81528304132859. The next prime is 81528304133039. The reversal of 81528304132861 is 16823140382518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 51042379916025 + 30485924216836 = 7144395^2 + 5521406^2 .

It is a cyclic number.

It is not a de Polignac number, because 81528304132861 - 2¹ = 81528304132859 is a prime.

Together with 81528304132859, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 81528304132799 and 81528304132808.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81528304132811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40764152066430 + 40764152066431.

It is an arithmetic number, because the mean of its divisors is an integer number (40764152066431).

Almost surely, 2^{81528304132861} is an apocalyptic number.

It is an amenable number.

81528304132861 is a deficient number, since it is larger than the sum of its proper divisors (1).

81528304132861 is an equidigital number, since it uses as much as digits as its factorization.

81528304132861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2211840, while the sum is 52.

The spelling of 81528304132861 in words is "eighty-one trillion, five hundred twenty-eight billion, three hundred four million, one hundred thirty-two thousand, eight hundred sixty-one".