81643193456 has 60 divisors (see below), whose sum is σ = 175122775800. Its totient is φ = 36843438720.

The previous prime is 81643193417. The next prime is 81643193483. The reversal of 81643193456 is 65439134618.

It is a super-2 number, since 2×81643193456² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 117410 + ... + 420798.

It is an arithmetic number, because the mean of its divisors is an integer number (2918712930).

Almost surely, 2^81643193456 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 81643193456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87561387900).

81643193456 is an abundant number, since it is smaller than the sum of its proper divisors (93479582344).

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

81643193456 is a wasteful number, since it uses less digits than its factorization.

81643193456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 303558 (or 303541 counting only the distinct ones).

The product of its digits is 1866240, while the sum is 50.

The spelling of 81643193456 in words is "eighty-one billion, six hundred forty-three million, one hundred ninety-three thousand, four hundred fifty-six".