81309435907 has 16 divisors (see below), whose sum is σ = 94834854400. Its totient is φ = 69683987016.

The previous prime is 81309435869. The next prime is 81309435913. The reversal of 81309435907 is 70953490318.

It is a de Polignac number, because none of the positive numbers 2^k-81309435907 is a prime.

It is a super-2 number, since 2×81309435907² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81309435007) 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, 3501778 + ... + 3524920.

It is an arithmetic number, because the mean of its divisors is an integer number (5927178400).

Almost surely, 2^81309435907 is an apocalyptic number.

81309435907 is a deficient number, since it is larger than the sum of its proper divisors (13525418493).

81309435907 is a wasteful number, since it uses less digits than its factorization.

81309435907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33407 (or 33393 counting only the distinct ones).

The product of its (nonzero) digits is 816480, while the sum is 49.

The spelling of 81309435907 in words is "eighty-one billion, three hundred nine million, four hundred thirty-five thousand, nine hundred seven".