81322133640 has 512 divisors, whose sum is σ = 290388810240. Its totient is φ = 17997824000.

The previous prime is 81322133639. The next prime is 81322133707. The reversal of 81322133640 is 4633122318.

It is a super-2 number, since 2×81322133640² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

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 127 ways as a sum of consecutive naturals, for example, 120120982 + ... + 120121658.

It is an arithmetic number, because the mean of its divisors is an integer number (567165645).

Almost surely, 2^81322133640 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 81322133640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (145194405120).

81322133640 is an abundant number, since it is smaller than the sum of its proper divisors (209066676600).

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

81322133640 is a wasteful number, since it uses less digits than its factorization.

81322133640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 873 (or 869 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 33.

Adding to 81322133640 its reverse (4633122318), we get a palindrome (85955255958).

The spelling of 81322133640 in words is "eighty-one billion, three hundred twenty-two million, one hundred thirty-three thousand, six hundred forty".