81789073 has 2 divisors, whose sum is σ = 81789074. Its totient is φ = 81789072.

The previous prime is 81789049. The next prime is 81789079. The reversal of 81789073 is 37098718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81414529 + 374544 = 9023^2 + 612^2 .

It is a cyclic number.

It is not a de Polignac number, because 81789073 - 2⁹ = 81788561 is a prime.

It is not a weakly prime, because it can be changed into another prime (81789079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40894536 + 40894537.

It is an arithmetic number, because the mean of its divisors is an integer number (40894537).

Almost surely, 2^81789073 is an apocalyptic number.

It is an amenable number.

81789073 is a deficient number, since it is larger than the sum of its proper divisors (1).

81789073 is an equidigital number, since it uses as much as digits as its factorization.

81789073 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 84672, while the sum is 43.

The square root of 81789073 is about 9043.7311437260. The cubic root of 81789073 is about 434.0753212232.

The spelling of 81789073 in words is "eighty-one million, seven hundred eighty-nine thousand, seventy-three".