81323239169 has 2 divisors, whose sum is σ = 81323239170. Its totient is φ = 81323239168.

The previous prime is 81323239157. The next prime is 81323239213. The reversal of 81323239169 is 96193232318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57216640000 + 24106599169 = 239200^2 + 155263^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81323239169 is a prime.

It is a super-2 number, since 2×81323239169² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (81323239369) 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, 40661619584 + 40661619585.

It is an arithmetic number, because the mean of its divisors is an integer number (40661619585).

Almost surely, 2^81323239169 is an apocalyptic number.

It is an amenable number.

81323239169 is a deficient number, since it is larger than the sum of its proper divisors (1).

81323239169 is an equidigital number, since it uses as much as digits as its factorization.

81323239169 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 419904, while the sum is 47.

The spelling of 81323239169 in words is "eighty-one billion, three hundred twenty-three million, two hundred thirty-nine thousand, one hundred sixty-nine".