81702594781 has 2 divisors, whose sum is σ = 81702594782. Its totient is φ = 81702594780.

The previous prime is 81702594709. The next prime is 81702594791. The reversal of 81702594781 is 18749520718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81305389881 + 397204900 = 285141^2 + 19930^2 .

It is a cyclic number.

It is not a de Polignac number, because 81702594781 - 2¹¹ = 81702592733 is a prime.

It is a super-2 number, since 2×81702594781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81702594791) 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, 40851297390 + 40851297391.

It is an arithmetic number, because the mean of its divisors is an integer number (40851297391).

Almost surely, 2^81702594781 is an apocalyptic number.

It is an amenable number.

81702594781 is a deficient number, since it is larger than the sum of its proper divisors (1).

81702594781 is an equidigital number, since it uses as much as digits as its factorization.

81702594781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1128960, while the sum is 52.

The spelling of 81702594781 in words is "eighty-one billion, seven hundred two million, five hundred ninety-four thousand, seven hundred eighty-one".