81521322157133 has 16 divisors (see below), whose sum is σ = 87457097856000. Its totient is φ = 75759710452272.

The previous prime is 81521322157063. The next prime is 81521322157141. The reversal of 81521322157133 is 33175122312518.

It is a cyclic number.

It is not a de Polignac number, because 81521322157133 - 2⁴² = 77123275646029 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81521322177133) 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, 133668023 + ... + 134276516.

It is an arithmetic number, because the mean of its divisors is an integer number (5466068616000).

Almost surely, 2^{81521322157133} is an apocalyptic number.

It is an amenable number.

81521322157133 is a deficient number, since it is larger than the sum of its proper divisors (5935775698867).

81521322157133 is a wasteful number, since it uses less digits than its factorization.

81521322157133 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267944864.

The product of its digits is 302400, while the sum is 44.

The spelling of 81521322157133 in words is "eighty-one trillion, five hundred twenty-one billion, three hundred twenty-two million, one hundred fifty-seven thousand, one hundred thirty-three".