81564846518 has 4 divisors (see below), whose sum is σ = 122347269780. Its totient is φ = 40782423258.

The previous prime is 81564846509. The next prime is 81564846551.

81564846518 is nontrivially palindromic in base 10.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20391211628 + ... + 20391211631.

It is an arithmetic number, because the mean of its divisors is an integer number (30586817445).

Almost surely, 2^81564846518 is an apocalyptic number.

81564846518 is a deficient number, since it is larger than the sum of its proper divisors (40782423262).

81564846518 is a wasteful number, since it uses less digits than its factorization.

81564846518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40782423261.

The product of its digits is 7372800, while the sum is 56.

The spelling of 81564846518 in words is "eighty-one billion, five hundred sixty-four million, eight hundred forty-six thousand, five hundred eighteen".