81324444840 has 32 divisors (see below), whose sum is σ = 243973334880. Its totient is φ = 21686518592.

The previous prime is 81324444827. The next prime is 81324444863. The reversal of 81324444840 is 4844442318.

It is a super-2 number, since 2×81324444840² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81324444792 and 81324444801.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 338851734 + ... + 338851973.

It is an arithmetic number, because the mean of its divisors is an integer number (7624166715).

Almost surely, 2^81324444840 is an apocalyptic number.

It is an amenable number.

81324444840 is an abundant number, since it is smaller than the sum of its proper divisors (162648890040).

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

81324444840 is a wasteful number, since it uses less digits than its factorization.

81324444840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677703721 (or 677703717 counting only the distinct ones).

The product of its (nonzero) digits is 393216, while the sum is 42.

The spelling of 81324444840 in words is "eighty-one billion, three hundred twenty-four million, four hundred forty-four thousand, eight hundred forty".