81743309 has 2 divisors, whose sum is σ = 81743310. Its totient is φ = 81743308.

The previous prime is 81743287. The next prime is 81743317. The reversal of 81743309 is 90334718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52345225 + 29398084 = 7235^2 + 5422^2 .

It is a cyclic number.

It is not a de Polignac number, because 81743309 - 2¹⁶ = 81677773 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81743369) 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, 40871654 + 40871655.

It is an arithmetic number, because the mean of its divisors is an integer number (40871655).

Almost surely, 2^81743309 is an apocalyptic number.

It is an amenable number.

81743309 is a deficient number, since it is larger than the sum of its proper divisors (1).

81743309 is an equidigital number, since it uses as much as digits as its factorization.

81743309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 35.

The square root of 81743309 is about 9041.2006392956. The cubic root of 81743309 is about 433.9943457396.

The spelling of 81743309 in words is "eighty-one million, seven hundred forty-three thousand, three hundred nine".