91166956897981 has 2 divisors, whose sum is σ = 91166956897982. Its totient is φ = 91166956897980.

The previous prime is 91166956897967. The next prime is 91166956897987. The reversal of 91166956897981 is 18979865966119.

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., 52250258092356 + 38916698805625 = 7228434^2 + 6238325^2 .

It is a cyclic number.

It is not a de Polignac number, because 91166956897981 - 2⁵ = 91166956897949 is a prime.

It is a super-3 number, since 3×91166956897981³ (a number of 43 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91166956897987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45583478448990 + 45583478448991.

It is an arithmetic number, because the mean of its divisors is an integer number (45583478448991).

Almost surely, 2^{91166956897981} is an apocalyptic number.

It is an amenable number.

91166956897981 is a deficient number, since it is larger than the sum of its proper divisors (1).

91166956897981 is an equidigital number, since it uses as much as digits as its factorization.

91166956897981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3174474240, while the sum is 85.

The spelling of 91166956897981 in words is "ninety-one trillion, one hundred sixty-six billion, nine hundred fifty-six million, eight hundred ninety-seven thousand, nine hundred eighty-one".