81044209 has 2 divisors, whose sum is σ = 81044210. Its totient is φ = 81044208.

The previous prime is 81044191. The next prime is 81044213. The reversal of 81044209 is 90244018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58982400 + 22061809 = 7680^2 + 4697^2 .

It is a cyclic number.

It is not a de Polignac number, because 81044209 - 2⁷ = 81044081 is a prime.

It is not a weakly prime, because it can be changed into another prime (81044269) 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, 40522104 + 40522105.

It is an arithmetic number, because the mean of its divisors is an integer number (40522105).

Almost surely, 2^81044209 is an apocalyptic number.

It is an amenable number.

81044209 is a deficient number, since it is larger than the sum of its proper divisors (1).

81044209 is an equidigital number, since it uses as much as digits as its factorization.

81044209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 81044209 is about 9002.4557205243. The cubic root of 81044209 is about 432.7535733328.

The spelling of 81044209 in words is "eighty-one million, forty-four thousand, two hundred nine".