81589702721 has 8 divisors (see below), whose sum is σ = 83755598784. Its totient is φ = 79436009520.

The previous prime is 81589702697. The next prime is 81589702723. The reversal of 81589702721 is 12720798518.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81589702721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81589702721.

It is not an unprimeable number, because it can be changed into a prime (81589702723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3037166 + ... + 3063911.

It is an arithmetic number, because the mean of its divisors is an integer number (10469449848).

Almost surely, 2^81589702721 is an apocalyptic number.

It is an amenable number.

81589702721 is a deficient number, since it is larger than the sum of its proper divisors (2165896063).

81589702721 is a wasteful number, since it uses less digits than its factorization.

81589702721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6101431.

The product of its (nonzero) digits is 564480, while the sum is 50.

The spelling of 81589702721 in words is "eighty-one billion, five hundred eighty-nine million, seven hundred two thousand, seven hundred twenty-one".