191585720681 has 2 divisors, whose sum is σ = 191585720682. Its totient is φ = 191585720680.

The previous prime is 191585720633. The next prime is 191585720701. The reversal of 191585720681 is 186027585191.

191585720681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 115406960656 + 76178760025 = 339716^2 + 276005^2 .

It is a cyclic number.

It is not a de Polignac number, because 191585720681 - 2²² = 191581526377 is a prime.

It is a super-2 number, since 2×191585720681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (191585720621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95792860340 + 95792860341.

It is an arithmetic number, because the mean of its divisors is an integer number (95792860341).

Almost surely, 2^191585720681 is an apocalyptic number.

It is an amenable number.

191585720681 is a deficient number, since it is larger than the sum of its proper divisors (1).

191585720681 is an equidigital number, since it uses as much as digits as its factorization.

191585720681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1209600, while the sum is 53.

The spelling of 191585720681 in words is "one hundred ninety-one billion, five hundred eighty-five million, seven hundred twenty thousand, six hundred eighty-one".