81946542887999 has 4 divisors (see below), whose sum is σ = 81946863975240. Its totient is φ = 81946221800760.

The previous prime is 81946542887977. The next prime is 81946542888043. The reversal of 81946542887999 is 99978824564918.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81946542887999 - 2¹² = 81946542883903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81946542877999) 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 3 ways as a sum of consecutive naturals, for example, 160160492 + ... + 160671329.

It is an arithmetic number, because the mean of its divisors is an integer number (20486715993810).

Almost surely, 2^{81946542887999} is an apocalyptic number.

81946542887999 is a deficient number, since it is larger than the sum of its proper divisors (321087241).

81946542887999 is a wasteful number, since it uses less digits than its factorization.

81946542887999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321087240.

The product of its digits is 22574039040, while the sum is 89.

The spelling of 81946542887999 in words is "eighty-one trillion, nine hundred forty-six billion, five hundred forty-two million, eight hundred eighty-seven thousand, nine hundred ninety-nine".