81573313727 has 4 divisors (see below), whose sum is σ = 84204710976. Its totient is φ = 78941916480.

The previous prime is 81573313721. The next prime is 81573313729. The reversal of 81573313727 is 72731337518.

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

It is a cyclic number.

It is not a de Polignac number, because 81573313727 - 2¹⁶ = 81573248191 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81573313721) 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, 1315698578 + ... + 1315698639.

It is an arithmetic number, because the mean of its divisors is an integer number (21051177744).

Almost surely, 2^81573313727 is an apocalyptic number.

81573313727 is a deficient number, since it is larger than the sum of its proper divisors (2631397249).

81573313727 is a wasteful number, since it uses less digits than its factorization.

81573313727 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2631397248.

The product of its digits is 740880, while the sum is 47.

The spelling of 81573313727 in words is "eighty-one billion, five hundred seventy-three million, three hundred thirteen thousand, seven hundred twenty-seven".