81982720733761 has 27 divisors (see below), whose sum is σ = 86945967631593. Its totient is φ = 77291520433920.

The previous prime is 81982720733701. The next prime is 81982720733779. The reversal of 81982720733761 is 16733702728918.

The square root of 81982720733761 is 9054431.

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

It can be written as a sum of positive squares in 4 ways, for example, as 12315319843761 + 69667400890000 = 3509319^2 + 8346700^2 .

It is not a de Polignac number, because 81982720733761 - 2⁷ = 81982720733633 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81982720733693 and 81982720733702.

It is not an unprimeable number, because it can be changed into a prime (81982720733701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 39395828241 + ... + 39395830321.

Almost surely, 2^{81982720733761} is an apocalyptic number.

81982720733761 is the 9054431-st square number.

81982720733761 is the 4527216-th centered octagonal number.

It is an amenable number.

81982720733761 is a deficient number, since it is larger than the sum of its proper divisors (4963246897832).

81982720733761 is an frugal number, since it uses more digits than its factorization.

81982720733761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4658 (or 2329 counting only the distinct ones).

The product of its (nonzero) digits is 42674688, while the sum is 64.

The spelling of 81982720733761 in words is "eighty-one trillion, nine hundred eighty-two billion, seven hundred twenty million, seven hundred thirty-three thousand, seven hundred sixty-one".