91830931981 has 2 divisors, whose sum is σ = 91830931982. Its totient is φ = 91830931980.

The previous prime is 91830931961. The next prime is 91830931987. The reversal of 91830931981 is 18913903819.

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., 91345390756 + 485541225 = 302234^2 + 22035^2 .

It is a cyclic number.

It is not a de Polignac number, because 91830931981 - 2⁵ = 91830931949 is a prime.

It is a super-2 number, since 2×91830931981² (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 (91830931987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45915465990 + 45915465991.

It is an arithmetic number, because the mean of its divisors is an integer number (45915465991).

Almost surely, 2^91830931981 is an apocalyptic number.

It is an amenable number.

91830931981 is a deficient number, since it is larger than the sum of its proper divisors (1).

91830931981 is an equidigital number, since it uses as much as digits as its factorization.

91830931981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 419904, while the sum is 52.

The spelling of 91830931981 in words is "ninety-one billion, eight hundred thirty million, nine hundred thirty-one thousand, nine hundred eighty-one".