81580352172221 has 32 divisors (see below), whose sum is σ = 95892714677760. Its totient is φ = 67937975894016.

The previous prime is 81580352172217. The next prime is 81580352172227. The reversal of 81580352172221 is 12227125308518.

It is a cyclic number.

It is not a de Polignac number, because 81580352172221 - 2² = 81580352172217 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81580352172227) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1626604481 + ... + 1626654633.

It is an arithmetic number, because the mean of its divisors is an integer number (2996647333680).

Almost surely, 2^{81580352172221} is an apocalyptic number.

It is an amenable number.

81580352172221 is a deficient number, since it is larger than the sum of its proper divisors (14312362505539).

81580352172221 is a wasteful number, since it uses less digits than its factorization.

81580352172221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59133.

The product of its (nonzero) digits is 537600, while the sum is 47.

The spelling of 81580352172221 in words is "eighty-one trillion, five hundred eighty billion, three hundred fifty-two million, one hundred seventy-two thousand, two hundred twenty-one".