8216660536781 has 2 divisors, whose sum is σ = 8216660536782. Its totient is φ = 8216660536780.

The previous prime is 8216660536741. The next prime is 8216660536783. The reversal of 8216660536781 is 1876350666128.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5972446811881 + 2244213724900 = 2443859^2 + 1498070^2 .

It is a cyclic number.

It is not a de Polignac number, because 8216660536781 - 2³⁴ = 8199480667597 is a prime.

It is a super-2 number, since 2×8216660536781² (a number of 27 digits) contains 22 as substring.

Together with 8216660536783, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 8216660536781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8216660536783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4108330268390 + 4108330268391.

It is an arithmetic number, because the mean of its divisors is an integer number (4108330268391).

Almost surely, 2^{8216660536781} is an apocalyptic number.

It is an amenable number.

8216660536781 is a deficient number, since it is larger than the sum of its proper divisors (1).

8216660536781 is an equidigital number, since it uses as much as digits as its factorization.

8216660536781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17418240, while the sum is 59.

The spelling of 8216660536781 in words is "eight trillion, two hundred sixteen billion, six hundred sixty million, five hundred thirty-six thousand, seven hundred eighty-one".