91705751681 has 2 divisors, whose sum is σ = 91705751682. Its totient is φ = 91705751680.

The previous prime is 91705751617. The next prime is 91705751699. The reversal of 91705751681 is 18615750719.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70851792400 + 20853959281 = 266180^2 + 144409^2 .

It is an emirp because it is prime and its reverse (18615750719) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91705751681 - 2⁶ = 91705751617 is a prime.

It is a super-2 number, since 2×91705751681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (91705751611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45852875840 + 45852875841.

It is an arithmetic number, because the mean of its divisors is an integer number (45852875841).

Almost surely, 2^91705751681 is an apocalyptic number.

It is an amenable number.

91705751681 is a deficient number, since it is larger than the sum of its proper divisors (1).

91705751681 is an equidigital number, since it uses as much as digits as its factorization.

91705751681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 529200, while the sum is 50.

The spelling of 91705751681 in words is "ninety-one billion, seven hundred five million, seven hundred fifty-one thousand, six hundred eighty-one".