81187044505 has 8 divisors (see below), whose sum is σ = 111342232512. Its totient is φ = 55671116208.

The previous prime is 81187044503. The next prime is 81187044557. The reversal of 81187044505 is 50544078118.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81187044505 - 2¹ = 81187044503 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81187044503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1159814887 + ... + 1159814956.

It is an arithmetic number, because the mean of its divisors is an integer number (13917779064).

Almost surely, 2^81187044505 is an apocalyptic number.

It is an amenable number.

81187044505 is a deficient number, since it is larger than the sum of its proper divisors (30155188007).

81187044505 is a wasteful number, since it uses less digits than its factorization.

81187044505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2319629855.

The product of its (nonzero) digits is 179200, while the sum is 43.

The spelling of 81187044505 in words is "eighty-one billion, one hundred eighty-seven million, forty-four thousand, five hundred five".