81680520427 has 4 divisors (see below), whose sum is σ = 89106022296. Its totient is φ = 74255018560.

The previous prime is 81680520409. The next prime is 81680520431. The reversal of 81680520427 is 72402508618.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81680520427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81680527427) 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 3 ways as a sum of consecutive naturals, for example, 3712750918 + ... + 3712750939.

It is an arithmetic number, because the mean of its divisors is an integer number (22276505574).

Almost surely, 2^81680520427 is an apocalyptic number.

81680520427 is a deficient number, since it is larger than the sum of its proper divisors (7425501869).

81680520427 is a wasteful number, since it uses less digits than its factorization.

81680520427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7425501868.

The product of its (nonzero) digits is 215040, while the sum is 43.

The spelling of 81680520427 in words is "eighty-one billion, six hundred eighty million, five hundred twenty thousand, four hundred twenty-seven".