81824209 has 16 divisors (see below), whose sum is σ = 85847040. Its totient is φ = 77933440.

The previous prime is 81824201. The next prime is 81824231. The reversal of 81824209 is 90242818.

It is a cyclic number.

It is not a de Polignac number, because 81824209 - 2³ = 81824201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81824201) 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 in 15 ways as a sum of consecutive naturals, for example, 428304 + ... + 428494.

It is an arithmetic number, because the mean of its divisors is an integer number (5365440).

Almost surely, 2^81824209 is an apocalyptic number.

It is an amenable number.

81824209 is a deficient number, since it is larger than the sum of its proper divisors (4022831).

81824209 is a wasteful number, since it uses less digits than its factorization.

81824209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 440.

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 81824209 is about 9045.6734962080. The cubic root of 81824209 is about 434.1374708741.

The spelling of 81824209 in words is "eighty-one million, eight hundred twenty-four thousand, two hundred nine".