81231268618 has 8 divisors (see below), whose sum is σ = 121906259748. Its totient is φ = 40595848704.

The previous prime is 81231268607. The next prime is 81231268619. The reversal of 81231268618 is 81686213218.

It can be written as a sum of positive squares in 2 ways, for example, as 69998872329 + 11232396289 = 264573^2 + 105983^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (81231268619) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 9887671 + ... + 9895882.

Almost surely, 2^81231268618 is an apocalyptic number.

81231268618 is a deficient number, since it is larger than the sum of its proper divisors (40674991130).

81231268618 is a wasteful number, since it uses less digits than its factorization.

81231268618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19785608.

The product of its digits is 221184, while the sum is 46.

The spelling of 81231268618 in words is "eighty-one billion, two hundred thirty-one million, two hundred sixty-eight thousand, six hundred eighteen".