81680520435 has 16 divisors (see below), whose sum is σ = 133154661024. Its totient is φ = 42741001472.

The previous prime is 81680520431. The next prime is 81680520463. The reversal of 81680520435 is 53402508618.

It is a cyclic number.

It is not a de Polignac number, because 81680520435 - 2² = 81680520431 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81680520431) 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 15 ways as a sum of consecutive naturals, for example, 51370602 + ... + 51372191.

It is an arithmetic number, because the mean of its divisors is an integer number (8322166314).

Almost surely, 2^81680520435 is an apocalyptic number.

81680520435 is a deficient number, since it is larger than the sum of its proper divisors (51474140589).

81680520435 is a wasteful number, since it uses less digits than its factorization.

81680520435 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102742854.

The product of its (nonzero) digits is 230400, while the sum is 42.

The spelling of 81680520435 in words is "eighty-one billion, six hundred eighty million, five hundred twenty thousand, four hundred thirty-five".