81583585221 has 16 divisors (see below), whose sum is σ = 108892002240. Its totient is φ = 54332150400.

The previous prime is 81583585219. The next prime is 81583585241. The reversal of 81583585221 is 12258538518.

It is not a de Polignac number, because 81583585221 - 2¹ = 81583585219 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81583585241) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18327046 + ... + 18331496.

It is an arithmetic number, because the mean of its divisors is an integer number (6805750140).

Almost surely, 2^81583585221 is an apocalyptic number.

It is an amenable number.

81583585221 is a deficient number, since it is larger than the sum of its proper divisors (27308417019).

81583585221 is a wasteful number, since it uses less digits than its factorization.

81583585221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9476.

The product of its digits is 768000, while the sum is 48.

The spelling of 81583585221 in words is "eighty-one billion, five hundred eighty-three million, five hundred eighty-five thousand, two hundred twenty-one".