81284309 has 2 divisors, whose sum is σ = 81284310. Its totient is φ = 81284308.

The previous prime is 81284257. The next prime is 81284311. The reversal of 81284309 is 90348218.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45941284 + 35343025 = 6778^2 + 5945^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81284309 is a prime.

Together with 81284311, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81284339) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40642154 + 40642155.

It is an arithmetic number, because the mean of its divisors is an integer number (40642155).

Almost surely, 2^81284309 is an apocalyptic number.

It is an amenable number.

81284309 is a deficient number, since it is larger than the sum of its proper divisors (1).

81284309 is an equidigital number, since it uses as much as digits as its factorization.

81284309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 81284309 is about 9015.7811087005. The cubic root of 81284309 is about 433.1805077786.

The spelling of 81284309 in words is "eighty-one million, two hundred eighty-four thousand, three hundred nine".