81973823487 has 4 divisors (see below), whose sum is σ = 109298431320. Its totient is φ = 54649215656.

The previous prime is 81973823447. The next prime is 81973823507. The reversal of 81973823487 is 78432837918.

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 81973823487 - 2⁶ = 81973823423 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81973823487.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81973823447) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13662303912 + ... + 13662303917.

It is an arithmetic number, because the mean of its divisors is an integer number (27324607830).

Almost surely, 2^81973823487 is an apocalyptic number.

81973823487 is a deficient number, since it is larger than the sum of its proper divisors (27324607833).

81973823487 is a wasteful number, since it uses less digits than its factorization.

81973823487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27324607832.

The product of its digits is 16257024, while the sum is 60.

The spelling of 81973823487 in words is "eighty-one billion, nine hundred seventy-three million, eight hundred twenty-three thousand, four hundred eighty-seven".