81561416518 has 16 divisors (see below), whose sum is σ = 122473504080. Its totient is φ = 40736941056.

The previous prime is 81561416513. The next prime is 81561416617.

81561416518 is nontrivially palindromic in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81561416513) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9902530 + ... + 9910762.

It is an arithmetic number, because the mean of its divisors is an integer number (7654594005).

Almost surely, 2^81561416518 is an apocalyptic number.

81561416518 is a deficient number, since it is larger than the sum of its proper divisors (40912087562).

81561416518 is a wasteful number, since it uses less digits than its factorization.

81561416518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12951.

The product of its digits is 230400, while the sum is 46.

The spelling of 81561416518 in words is "eighty-one billion, five hundred sixty-one million, four hundred sixteen thousand, five hundred eighteen".