81571522517518 has 16 divisors (see below), whose sum is σ = 134661918110256. Its totient is φ = 36749841197440.

The previous prime is 81571522517417. The next prime is 81571522517587.

It is a happy number.

81571522517518 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×81571522517518² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16406176621 + ... + 16406181592.

It is an arithmetic number, because the mean of its divisors is an integer number (8416369881891).

Almost surely, 2^{81571522517518} is an apocalyptic number.

81571522517518 is a deficient number, since it is larger than the sum of its proper divisors (53090395592738).

81571522517518 is a wasteful number, since it uses less digits than its factorization.

81571522517518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32812358339.

The product of its digits is 7840000, while the sum is 58.

The spelling of 81571522517518 in words is "eighty-one trillion, five hundred seventy-one billion, five hundred twenty-two million, five hundred seventeen thousand, five hundred eighteen".