81394891 has 2 divisors, whose sum is σ = 81394892. Its totient is φ = 81394890.

The previous prime is 81394867. The next prime is 81394903. The reversal of 81394891 is 19849318.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81394891 - 2⁷ = 81394763 is a prime.

It is not a weakly prime, because it can be changed into another prime (81344891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40697445 + 40697446.

It is an arithmetic number, because the mean of its divisors is an integer number (40697446).

Almost surely, 2^81394891 is an apocalyptic number.

81394891 is a deficient number, since it is larger than the sum of its proper divisors (1).

81394891 is an equidigital number, since it uses as much as digits as its factorization.

81394891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 43.

The square root of 81394891 is about 9021.9117153739. The cubic root of 81394891 is about 433.3768567067.

The spelling of 81394891 in words is "eighty-one million, three hundred ninety-four thousand, eight hundred ninety-one".