81649694618 has 16 divisors (see below), whose sum is σ = 123810054120. Its totient is φ = 40380480000.

The previous prime is 81649694579. The next prime is 81649694741.

81649694618 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in 4 ways, for example, as 69177942289 + 12471752329 = 263017^2 + 111677^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3518 + ... + 404118.

Almost surely, 2^81649694618 is an apocalyptic number.

81649694618 is a deficient number, since it is larger than the sum of its proper divisors (42160359502).

81649694618 is a wasteful number, since it uses less digits than its factorization.

81649694618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401713.

The product of its digits is 17915904, while the sum is 62.

The spelling of 81649694618 in words is "eighty-one billion, six hundred forty-nine million, six hundred ninety-four thousand, six hundred eighteen".