81324320 has 288 divisors, whose sum is σ = 260620416. Its totient is φ = 23654400.

The previous prime is 81324319. The next prime is 81324403. The reversal of 81324320 is 2342318.

It is a super-2 number, since 2×81324320² = 13227290046924800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 1983500 + ... + 1983540.

It is an arithmetic number, because the mean of its divisors is an integer number (904932).

Almost surely, 2^81324320 is an apocalyptic number.

81324320 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81324320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130310208).

81324320 is an abundant number, since it is smaller than the sum of its proper divisors (179296096).

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

81324320 is a wasteful number, since it uses less digits than its factorization.

81324320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104 (or 89 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 81324320 is about 9017.9997782213. Note that the first 3 decimals coincide. The cubic root of 81324320 is about 433.2515716879.

Adding to 81324320 its reverse (2342318), we get a palindrome (83666638).

The spelling of 81324320 in words is "eighty-one million, three hundred twenty-four thousand, three hundred twenty".