81616051202809 has 2 divisors, whose sum is σ = 81616051202810. Its totient is φ = 81616051202808.

The previous prime is 81616051202729. The next prime is 81616051202827. The reversal of 81616051202809 is 90820215061618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 44549324022784 + 37066727180025 = 6674528^2 + 6088245^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81616051202809 is a prime.

It is a super-2 number, since 2×81616051202809² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81616051202849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40808025601404 + 40808025601405.

It is an arithmetic number, because the mean of its divisors is an integer number (40808025601405).

Almost surely, 2^{81616051202809} is an apocalyptic number.

It is an amenable number.

81616051202809 is a deficient number, since it is larger than the sum of its proper divisors (1).

81616051202809 is an equidigital number, since it uses as much as digits as its factorization.

81616051202809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 414720, while the sum is 49.

The spelling of 81616051202809 in words is "eighty-one trillion, six hundred sixteen billion, fifty-one million, two hundred two thousand, eight hundred nine".