81329887560221 has 4 divisors (see below), whose sum is σ = 81337623696252. Its totient is φ = 81322151424192.

The previous prime is 81329887560169. The next prime is 81329887560227. The reversal of 81329887560221 is 12206578892318.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12742686696100 + 68587200864121 = 3569690^2 + 8281739^2 .

It is a cyclic number.

It is not a de Polignac number, because 81329887560221 - 2³⁰ = 81328813818397 is a prime.

It is a super-2 number, since 2×81329887560221² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81329887560227) 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, 3868052246 + ... + 3868073271.

It is an arithmetic number, because the mean of its divisors is an integer number (20334405924063).

Almost surely, 2^{81329887560221} is an apocalyptic number.

It is an amenable number.

81329887560221 is a deficient number, since it is larger than the sum of its proper divisors (7736136031).

81329887560221 is a wasteful number, since it uses less digits than its factorization.

81329887560221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7736136030.

The product of its (nonzero) digits is 23224320, while the sum is 62.

The spelling of 81329887560221 in words is "eighty-one trillion, three hundred twenty-nine billion, eight hundred eighty-seven million, five hundred sixty thousand, two hundred twenty-one".