81547805739 has 8 divisors (see below), whose sum is σ = 108957404160. Its totient is φ = 54251705576.

The previous prime is 81547805719. The next prime is 81547805753. The reversal of 81547805739 is 93750874518.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 81547805739 - 2⁸ = 81547805483 is a prime.

It is a super-2 number, since 2×81547805739² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81547805719) 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, 28372887 + ... + 28375760.

It is an arithmetic number, because the mean of its divisors is an integer number (13619675520).

Almost surely, 2^81547805739 is an apocalyptic number.

81547805739 is a deficient number, since it is larger than the sum of its proper divisors (27409598421).

81547805739 is a wasteful number, since it uses less digits than its factorization.

81547805739 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56749129.

The product of its (nonzero) digits is 8467200, while the sum is 57.

The spelling of 81547805739 in words is "eighty-one billion, five hundred forty-seven million, eight hundred five thousand, seven hundred thirty-nine".