81049729 has 2 divisors, whose sum is σ = 81049730. Its totient is φ = 81049728.

The previous prime is 81049691. The next prime is 81049733. The reversal of 81049729 is 92794018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81000000 + 49729 = 9000^2 + 223^2 .

It is a cyclic number.

It is not a de Polignac number, because 81049729 - 2¹⁹ = 80525441 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81049691 and 81049700.

It is not a weakly prime, because it can be changed into another prime (81049739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40524864 + 40524865.

It is an arithmetic number, because the mean of its divisors is an integer number (40524865).

Almost surely, 2^81049729 is an apocalyptic number.

It is an amenable number.

81049729 is a deficient number, since it is larger than the sum of its proper divisors (1).

81049729 is an equidigital number, since it uses as much as digits as its factorization.

81049729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 81049729 is about 9002.7622983171. The cubic root of 81049729 is about 432.7633981988.

The spelling of 81049729 in words is "eighty-one million, forty-nine thousand, seven hundred twenty-nine".