81761592217 has 2 divisors, whose sum is σ = 81761592218. Its totient is φ = 81761592216.

The previous prime is 81761592181. The next prime is 81761592223. The reversal of 81761592217 is 71229516718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 68321595456 + 13439996761 = 261384^2 + 115931^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81761592217 is a prime.

It is not a weakly prime, because it can be changed into another prime (81761592247) 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, 40880796108 + 40880796109.

It is an arithmetic number, because the mean of its divisors is an integer number (40880796109).

Almost surely, 2^81761592217 is an apocalyptic number.

It is an amenable number.

81761592217 is a deficient number, since it is larger than the sum of its proper divisors (1).

81761592217 is an equidigital number, since it uses as much as digits as its factorization.

81761592217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 423360, while the sum is 49.

The spelling of 81761592217 in words is "eighty-one billion, seven hundred sixty-one million, five hundred ninety-two thousand, two hundred seventeen".