81744672754861 has 2 divisors, whose sum is σ = 81744672754862. Its totient is φ = 81744672754860.

The previous prime is 81744672754831. The next prime is 81744672754873. The reversal of 81744672754861 is 16845727644718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81536023872900 + 208648881961 = 9029730^2 + 456781^2 .

It is a cyclic number.

It is not a de Polignac number, because 81744672754861 - 2³¹ = 81742525271213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81744672754831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40872336377430 + 40872336377431.

It is an arithmetic number, because the mean of its divisors is an integer number (40872336377431).

Almost surely, 2^{81744672754861} is an apocalyptic number.

It is an amenable number.

81744672754861 is a deficient number, since it is larger than the sum of its proper divisors (1).

81744672754861 is an equidigital number, since it uses as much as digits as its factorization.

81744672754861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 505774080, while the sum is 70.

The spelling of 81744672754861 in words is "eighty-one trillion, seven hundred forty-four billion, six hundred seventy-two million, seven hundred fifty-four thousand, eight hundred sixty-one".