81967378399 has 2 divisors, whose sum is σ = 81967378400. Its totient is φ = 81967378398.

The previous prime is 81967378253. The next prime is 81967378457. The reversal of 81967378399 is 99387376918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81967378399 - 2¹⁵ = 81967345631 is a prime.

It is a super-2 number, since 2×81967378399² (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 (81967378699) 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, 40983689199 + 40983689200.

It is an arithmetic number, because the mean of its divisors is an integer number (40983689200).

Almost surely, 2^81967378399 is an apocalyptic number.

81967378399 is a deficient number, since it is larger than the sum of its proper divisors (1).

81967378399 is an equidigital number, since it uses as much as digits as its factorization.

81967378399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 123451776, while the sum is 70.

The spelling of 81967378399 in words is "eighty-one billion, nine hundred sixty-seven million, three hundred seventy-eight thousand, three hundred ninety-nine".