81693644041 has 45 divisors (see below), whose sum is σ = 92896652289. Its totient is φ = 71834820288.

The previous prime is 81693644029. The next prime is 81693644059. The reversal of 81693644041 is 14044639618.

The square root of 81693644041 is 285821.

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

It can be written as a sum of positive squares in 2 ways, for example, as 25353874441 + 56339769600 = 159229^2 + 237360^2 .

It is not a de Polignac number, because 81693644041 - 2⁹ = 81693643529 is a prime.

It is a super-2 number, since 2×81693644041² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81693643982 and 81693644000.

It is not an unprimeable number, because it can be changed into a prime (81693654041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 1899852166 + ... + 1899852208.

Almost surely, 2^81693644041 is an apocalyptic number.

81693644041 is the 285821-st square number.

81693644041 is the 142911-st centered octagonal number.

It is an amenable number.

81693644041 is a deficient number, since it is larger than the sum of its proper divisors (11203008248).

81693644041 is an frugal number, since it uses more digits than its factorization.

81693644041 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200 (or 83 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 46.

The spelling of 81693644041 in words is "eighty-one billion, six hundred ninety-three million, six hundred forty-four thousand, forty-one".