81213535887 has 24 divisors (see below), whose sum is σ = 119074706352. Its totient is φ = 49199230080.

The previous prime is 81213535867. The next prime is 81213535927. The reversal of 81213535887 is 78853531218.

It is not a de Polignac number, because 81213535887 - 2⁸ = 81213535631 is a prime.

It is a super-2 number, since 2×81213535887² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81213535817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 821913 + ... + 915405.

It is an arithmetic number, because the mean of its divisors is an integer number (4961446098).

Almost surely, 2^81213535887 is an apocalyptic number.

81213535887 is a deficient number, since it is larger than the sum of its proper divisors (37861170465).

81213535887 is a wasteful number, since it uses less digits than its factorization.

81213535887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95911 (or 95900 counting only the distinct ones).

The product of its digits is 1612800, while the sum is 51.

The spelling of 81213535887 in words is "eighty-one billion, two hundred thirteen million, five hundred thirty-five thousand, eight hundred eighty-seven".