81816221933824 has 81 divisors (see below), whose sum is σ = 189978523932141. Its totient is φ = 35063660943360.

The previous prime is 81816221933807. The next prime is 81816221933861. The reversal of 81816221933824 is 42833912261818.

The square root of 81816221933824 is 9045232.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 19363238535424 + 62452983398400 = 4400368^2 + 7902720^2 .

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 8 ways as a sum of consecutive naturals, for example, 1013025604 + ... + 1013106364.

Almost surely, 2^{81816221933824} is an apocalyptic number.

81816221933824 is the 9045232-nd square number.

It is an amenable number.

81816221933824 is an abundant number, since it is smaller than the sum of its proper divisors (108162301998317).

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

81816221933824 is an frugal number, since it uses more digits than its factorization.

81816221933824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161552 (or 80770 counting only the distinct ones).

The product of its digits is 7962624, while the sum is 58.

The spelling of 81816221933824 in words is "eighty-one trillion, eight hundred sixteen billion, two hundred twenty-one million, nine hundred thirty-three thousand, eight hundred twenty-four".