91166956397981 has 2 divisors, whose sum is σ = 91166956397982. Its totient is φ = 91166956397980.

The previous prime is 91166956397939. The next prime is 91166956398019. The reversal of 91166956397981 is 18979365966119.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59159310697081 + 32007645700900 = 7691509^2 + 5657530^2 .

It is a cyclic number.

It is not a de Polignac number, because 91166956397981 - 2¹⁴ = 91166956381597 is a prime.

It is a super-2 number, since 2×91166956397981² (a number of 29 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 91166956397896 and 91166956397905.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91166956897981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45583478198990 + 45583478198991.

It is an arithmetic number, because the mean of its divisors is an integer number (45583478198991).

Almost surely, 2^{91166956397981} is an apocalyptic number.

It is an amenable number.

91166956397981 is a deficient number, since it is larger than the sum of its proper divisors (1).

91166956397981 is an equidigital number, since it uses as much as digits as its factorization.

91166956397981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1190427840, while the sum is 80.

The spelling of 91166956397981 in words is "ninety-one trillion, one hundred sixty-six billion, nine hundred fifty-six million, three hundred ninety-seven thousand, nine hundred eighty-one".