81985247541 has 6 divisors (see below), whose sum is σ = 118423135350. Its totient is φ = 54656831688.

The previous prime is 81985247501. The next prime is 81985247567. The reversal of 81985247541 is 14574258918.

81985247541 is a `hidden beast` number, since 8 + 1 + 9 + 8 + 52 + 47 + 541 = 666.

It can be written as a sum of positive squares in only one way, i.e., 78710546916 + 3274700625 = 280554^2 + 57225^2 .

It is not a de Polignac number, because 81985247541 - 2³¹ = 79837763893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81985247501) 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 5 ways as a sum of consecutive naturals, for example, 4554735966 + ... + 4554735983.

It is an arithmetic number, because the mean of its divisors is an integer number (19737189225).

Almost surely, 2^81985247541 is an apocalyptic number.

It is an amenable number.

81985247541 is a deficient number, since it is larger than the sum of its proper divisors (36437887809).

81985247541 is a wasteful number, since it uses less digits than its factorization.

81985247541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9109471955 (or 9109471952 counting only the distinct ones).

The product of its digits is 3225600, while the sum is 54.

The spelling of 81985247541 in words is "eighty-one billion, nine hundred eighty-five million, two hundred forty-seven thousand, five hundred forty-one".