81680520399 has 8 divisors (see below), whose sum is σ = 108944252592. Its totient is φ = 54435234240.

The previous prime is 81680520391. The next prime is 81680520409. The reversal of 81680520399 is 99302508618.

It is a happy number.

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

It is not a de Polignac number, because 81680520399 - 2³ = 81680520391 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81680520391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4601172 + ... + 4618889.

It is an arithmetic number, because the mean of its divisors is an integer number (13618031574).

Almost surely, 2^81680520399 is an apocalyptic number.

81680520399 is a deficient number, since it is larger than the sum of its proper divisors (27263732193).

81680520399 is a wasteful number, since it uses less digits than its factorization.

81680520399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9223017.

The product of its (nonzero) digits is 933120, while the sum is 51.

The spelling of 81680520399 in words is "eighty-one billion, six hundred eighty million, five hundred twenty thousand, three hundred ninety-nine".