91855212689 has 2 divisors, whose sum is σ = 91855212690. Its totient is φ = 91855212688.

The previous prime is 91855212671. The next prime is 91855212697. The reversal of 91855212689 is 98621255819.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51209427025 + 40645785664 = 226295^2 + 201608^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91855212689 is a prime.

It is a super-2 number, since 2×91855212689² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (91855212989) 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, 45927606344 + 45927606345.

It is an arithmetic number, because the mean of its divisors is an integer number (45927606345).

Almost surely, 2^91855212689 is an apocalyptic number.

It is an amenable number.

91855212689 is a deficient number, since it is larger than the sum of its proper divisors (1).

91855212689 is an equidigital number, since it uses as much as digits as its factorization.

91855212689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3110400, while the sum is 56.

The spelling of 91855212689 in words is "ninety-one billion, eight hundred fifty-five million, two hundred twelve thousand, six hundred eighty-nine".