81260661061 has 2 divisors, whose sum is σ = 81260661062. Its totient is φ = 81260661060.

The previous prime is 81260661059. The next prime is 81260661103. The reversal of 81260661061 is 16016606218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72041780836 + 9218880225 = 268406^2 + 96015^2 .

It is a cyclic number.

It is not a de Polignac number, because 81260661061 - 2¹ = 81260661059 is a prime.

Together with 81260661059, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 81260661061.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81260661161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40630330530 + 40630330531.

It is an arithmetic number, because the mean of its divisors is an integer number (40630330531).

Almost surely, 2^81260661061 is an apocalyptic number.

It is an amenable number.

81260661061 is a deficient number, since it is larger than the sum of its proper divisors (1).

81260661061 is an equidigital number, since it uses as much as digits as its factorization.

81260661061 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 37.

The spelling of 81260661061 in words is "eighty-one billion, two hundred sixty million, six hundred sixty-one thousand, sixty-one".