81976320499 has 4 divisors (see below), whose sum is σ = 83365749720. Its totient is φ = 80586891280.

The previous prime is 81976320463. The next prime is 81976320539. The reversal of 81976320499 is 99402367918.

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 81976320499 - 2¹¹ = 81976318451 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81976321499) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 694714522 + ... + 694714639.

It is an arithmetic number, because the mean of its divisors is an integer number (20841437430).

Almost surely, 2^81976320499 is an apocalyptic number.

81976320499 is a deficient number, since it is larger than the sum of its proper divisors (1389429221).

81976320499 is a wasteful number, since it uses less digits than its factorization.

81976320499 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1389429220.

The product of its (nonzero) digits is 5878656, while the sum is 58.

The spelling of 81976320499 in words is "eighty-one billion, nine hundred seventy-six million, three hundred twenty thousand, four hundred ninety-nine".