81207870218 has 12 divisors (see below), whose sum is σ = 127338240498. Its totient is φ = 38838546120.

The previous prime is 81207870193. The next prime is 81207870329.

81207870218 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in only one way, i.e., 40882009249 + 40325860969 = 202193^2 + 200813^2 .

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 38376953 + ... + 38379068.

Almost surely, 2^81207870218 is an apocalyptic number.

81207870218 is a deficient number, since it is larger than the sum of its proper divisors (46130370280).

81207870218 is a wasteful number, since it uses less digits than its factorization.

81207870218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76756069 (or 76756046 counting only the distinct ones).

The product of its (nonzero) digits is 100352, while the sum is 44.

The spelling of 81207870218 in words is "eighty-one billion, two hundred seven million, eight hundred seventy thousand, two hundred eighteen".