81323109 has 24 divisors (see below), whose sum is σ = 139222720. Its totient is φ = 46469376.

The previous prime is 81323089. The next prime is 81323111. The reversal of 81323109 is 90132318.

It is not a de Polignac number, because 81323109 - 2⁷ = 81322981 is a prime.

It is a super-2 number, since 2×81323109² = 13226896114851762, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81323129) 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 in 23 ways as a sum of consecutive naturals, for example, 22204 + ... + 25605.

Almost surely, 2^81323109 is an apocalyptic number.

It is an amenable number.

81323109 is a deficient number, since it is larger than the sum of its proper divisors (57899611).

81323109 is an equidigital number, since it uses as much as digits as its factorization.

81323109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47831 (or 47819 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 81323109 is about 9017.9326344789. The cubic root of 81323109 is about 433.2494211616.

The spelling of 81323109 in words is "eighty-one million, three hundred twenty-three thousand, one hundred nine".