81075438617 has 2 divisors, whose sum is σ = 81075438618. Its totient is φ = 81075438616.

The previous prime is 81075438583. The next prime is 81075438629. The reversal of 81075438617 is 71683457018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72973458496 + 8101980121 = 270136^2 + 90011^2 .

It is a cyclic number.

It is not a de Polignac number, because 81075438617 - 2³⁶ = 12355961881 is a prime.

It is a super-3 number, since 3×81075438617³ (a number of 34 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (81075434617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40537719308 + 40537719309.

It is an arithmetic number, because the mean of its divisors is an integer number (40537719309).

Almost surely, 2^81075438617 is an apocalyptic number.

It is an amenable number.

81075438617 is a deficient number, since it is larger than the sum of its proper divisors (1).

81075438617 is an equidigital number, since it uses as much as digits as its factorization.

81075438617 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1128960, while the sum is 50.

The spelling of 81075438617 in words is "eighty-one billion, seventy-five million, four hundred thirty-eight thousand, six hundred seventeen".