81543978085 has 32 divisors (see below), whose sum is σ = 98973705600. Its totient is φ = 64494178560.

The previous prime is 81543978059. The next prime is 81543978107. The reversal of 81543978085 is 58087934518.

It is not a de Polignac number, because 81543978085 - 2⁵ = 81543978053 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 176884755 + ... + 176885215.

It is an arithmetic number, because the mean of its divisors is an integer number (3092928300).

Almost surely, 2^81543978085 is an apocalyptic number.

It is an amenable number.

81543978085 is a deficient number, since it is larger than the sum of its proper divisors (17429727515).

81543978085 is a wasteful number, since it uses less digits than its factorization.

81543978085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1461.

The product of its (nonzero) digits is 9676800, while the sum is 58.

The spelling of 81543978085 in words is "eighty-one billion, five hundred forty-three million, nine hundred seventy-eight thousand, eighty-five".