81343309 has 2 divisors, whose sum is σ = 81343310. Its totient is φ = 81343308.

The previous prime is 81343307. The next prime is 81343331. The reversal of 81343309 is 90334318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77827684 + 3515625 = 8822^2 + 1875^2 .

It is a cyclic number.

It is not a de Polignac number, because 81343309 - 2¹ = 81343307 is a prime.

Together with 81343307, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81343307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40671654 + 40671655.

It is an arithmetic number, because the mean of its divisors is an integer number (40671655).

Almost surely, 2^81343309 is an apocalyptic number.

It is an amenable number.

81343309 is a deficient number, since it is larger than the sum of its proper divisors (1).

81343309 is an equidigital number, since it uses as much as digits as its factorization.

81343309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 81343309 is about 9019.0525555626. The cubic root of 81343309 is about 433.2852900714.

The spelling of 81343309 in words is "eighty-one million, three hundred forty-three thousand, three hundred nine".