81718255639061 has 2 divisors, whose sum is σ = 81718255639062. Its totient is φ = 81718255639060.

The previous prime is 81718255638991. The next prime is 81718255639117. The reversal of 81718255639061 is 16093655281718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81522281202961 + 195974436100 = 9028969^2 + 442690^2 .

It is a cyclic number.

It is not a de Polignac number, because 81718255639061 - 2¹⁴ = 81718255622677 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81718255638985 and 81718255639003.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81718255689061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40859127819530 + 40859127819531.

It is an arithmetic number, because the mean of its divisors is an integer number (40859127819531).

Almost surely, 2^{81718255639061} is an apocalyptic number.

It is an amenable number.

81718255639061 is a deficient number, since it is larger than the sum of its proper divisors (1).

81718255639061 is an equidigital number, since it uses as much as digits as its factorization.

81718255639061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21772800, while the sum is 62.

The spelling of 81718255639061 in words is "eighty-one trillion, seven hundred eighteen billion, two hundred fifty-five million, six hundred thirty-nine thousand, sixty-one".