81538732281 has 16 divisors (see below), whose sum is σ = 109822078080. Its totient is φ = 53807539200.

The previous prime is 81538732271. The next prime is 81538732321. The reversal of 81538732281 is 18223783518.

It is not a de Polignac number, because 81538732281 - 2⁶ = 81538732217 is a prime.

It is a super-2 number, since 2×81538732281² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81538732281.

It is not an unprimeable number, because it can be changed into a prime (81538732211) 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 15 ways as a sum of consecutive naturals, for example, 1268196 + ... + 1330938.

It is an arithmetic number, because the mean of its divisors is an integer number (6863879880).

Almost surely, 2^81538732281 is an apocalyptic number.

It is an amenable number.

81538732281 is a deficient number, since it is larger than the sum of its proper divisors (28283345799).

81538732281 is a wasteful number, since it uses less digits than its factorization.

81538732281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67136.

The product of its digits is 645120, while the sum is 48.

The spelling of 81538732281 in words is "eighty-one billion, five hundred thirty-eight million, seven hundred thirty-two thousand, two hundred eighty-one".