81320643307 has 4 divisors (see below), whose sum is σ = 81337213840. Its totient is φ = 81304072776.

The previous prime is 81320643281. The next prime is 81320643311. The reversal of 81320643307 is 70334602318.

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-81320643307 is a prime.

It is a super-3 number, since 3×81320643307³ (a number of 34 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81320643337) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8277903 + ... + 8287720.

It is an arithmetic number, because the mean of its divisors is an integer number (20334303460).

Almost surely, 2^81320643307 is an apocalyptic number.

81320643307 is a deficient number, since it is larger than the sum of its proper divisors (16570533).

81320643307 is a wasteful number, since it uses less digits than its factorization.

81320643307 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16570532.

The product of its (nonzero) digits is 72576, while the sum is 37.

The spelling of 81320643307 in words is "eighty-one billion, three hundred twenty million, six hundred forty-three thousand, three hundred seven".