81541778487 has 48 divisors (see below), whose sum is σ = 122313233952. Its totient is φ = 48021050880.

The previous prime is 81541778473. The next prime is 81541778489. The reversal of 81541778487 is 78487714518.

It is not a de Polignac number, because 81541778487 - 2⁸ = 81541778231 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81541778487.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81541778489) 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 47 ways as a sum of consecutive naturals, for example, 3244333 + ... + 3269369.

It is an arithmetic number, because the mean of its divisors is an integer number (2548192374).

Almost surely, 2^81541778487 is an apocalyptic number.

81541778487 is a deficient number, since it is larger than the sum of its proper divisors (40771455465).

81541778487 is a wasteful number, since it uses less digits than its factorization.

81541778487 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25188 (or 25151 counting only the distinct ones).

The product of its digits is 14049280, while the sum is 60.

The spelling of 81541778487 in words is "eighty-one billion, five hundred forty-one million, seven hundred seventy-eight thousand, four hundred eighty-seven".