81515851518 has 16 divisors (see below), whose sum is σ = 165794952960. Its totient is φ = 26711408856.

The previous prime is 81515851481. The next prime is 81515851531.

81515851518 is nontrivially palindromic in base 10.

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, 115135030 + ... + 115135737.

It is an arithmetic number, because the mean of its divisors is an integer number (10362184560).

Almost surely, 2^81515851518 is an apocalyptic number.

81515851518 is an abundant number, since it is smaller than the sum of its proper divisors (84279101442).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81515851518 is a wasteful number, since it uses less digits than its factorization.

81515851518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230270831.

The product of its digits is 320000, while the sum is 48.

The spelling of 81515851518 in words is "eighty-one billion, five hundred fifteen million, eight hundred fifty-one thousand, five hundred eighteen".