81653635618 has 8 divisors (see below), whose sum is σ = 122481768348. Its totient is φ = 40826379504.

The previous prime is 81653635601. The next prime is 81653635619.

81653635618 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in 2 ways, for example, as 81531378369 + 122257249 = 285537^2 + 11057^2 .

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 (81653635619) 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, 116580 + ... + 420592.

Almost surely, 2^81653635618 is an apocalyptic number.

81653635618 is a deficient number, since it is larger than the sum of its proper divisors (40828132730).

81653635618 is a wasteful number, since it uses less digits than its factorization.

81653635618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 438308.

The product of its digits is 3110400, while the sum is 52.

The spelling of 81653635618 in words is "eighty-one billion, six hundred fifty-three million, six hundred thirty-five thousand, six hundred eighteen".