81040320 has 168 divisors, whose sum is σ = 293613840. Its totient is φ = 20459520.

The previous prime is 81040307. The next prime is 81040321. The reversal of 81040320 is 2304018.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 81040293 and 81040302.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81040321) 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 23 ways as a sum of consecutive naturals, for example, 53980 + ... + 55460.

Almost surely, 2^81040320 is an apocalyptic number.

81040320 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 81040320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (146806920).

81040320 is an abundant number, since it is smaller than the sum of its proper divisors (212573520).

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

81040320 is a wasteful number, since it uses less digits than its factorization.

81040320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1523 (or 1510 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 81040320 is about 9002.2397213138. The cubic root of 81040320 is about 432.7466511620.

Adding to 81040320 its reverse (2304018), we get a palindrome (83344338).

The spelling of 81040320 in words is "eighty-one million, forty thousand, three hundred twenty".