81323320 has 64 divisors (see below), whose sum is σ = 201690720. Its totient is φ = 29320704.

The previous prime is 81323293. The next prime is 81323353. The reversal of 81323320 is 2332318.

It is a happy number.

It is a super-2 number, since 2×81323320² = 13226964751644800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81323291 and 81323300.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 20542 + ... + 24178.

Almost surely, 2^81323320 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81323320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100845360).

81323320 is an abundant number, since it is smaller than the sum of its proper divisors (120367400).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81323320 is a wasteful number, since it uses less digits than its factorization.

81323320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3704 (or 3700 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 81323320 is about 9017.9443333833. The cubic root of 81323320 is about 433.2497958626.

Adding to 81323320 its reverse (2332318), we get a palindrome (83655638).

The spelling of 81323320 in words is "eighty-one million, three hundred twenty-three thousand, three hundred twenty".