81864407687 has 4 divisors (see below), whose sum is σ = 81878390736. Its totient is φ = 81850424640.

The previous prime is 81864407663. The next prime is 81864407753. The reversal of 81864407687 is 78670446818.

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 81864407687 - 2¹² = 81864403591 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 (81864407887) 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, 6982739 + ... + 6994452.

It is an arithmetic number, because the mean of its divisors is an integer number (20469597684).

Almost surely, 2^81864407687 is an apocalyptic number.

81864407687 is a deficient number, since it is larger than the sum of its proper divisors (13983049).

81864407687 is a wasteful number, since it uses less digits than its factorization.

81864407687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13983048.

The product of its (nonzero) digits is 14450688, while the sum is 59.

The spelling of 81864407687 in words is "eighty-one billion, eight hundred sixty-four million, four hundred seven thousand, six hundred eighty-seven".