91401611981 has 2 divisors, whose sum is σ = 91401611982. Its totient is φ = 91401611980.

The previous prime is 91401611947. The next prime is 91401612047. The reversal of 91401611981 is 18911610419.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 88024956100 + 3376655881 = 296690^2 + 58109^2 .

It is a cyclic number.

It is not a de Polignac number, because 91401611981 - 2³⁴ = 74221742797 is a prime.

It is a super-2 number, since 2×91401611981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91401611911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45700805990 + 45700805991.

It is an arithmetic number, because the mean of its divisors is an integer number (45700805991).

Almost surely, 2^91401611981 is an apocalyptic number.

It is an amenable number.

91401611981 is a deficient number, since it is larger than the sum of its proper divisors (1).

91401611981 is an equidigital number, since it uses as much as digits as its factorization.

91401611981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 41.

The spelling of 91401611981 in words is "ninety-one billion, four hundred one million, six hundred eleven thousand, nine hundred eighty-one".