81668507878235 has 4 divisors (see below), whose sum is σ = 98002209453888. Its totient is φ = 65334806302584.

The previous prime is 81668507878163. The next prime is 81668507878253. The reversal of 81668507878235 is 53287870586618.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81668507878235 - 2¹⁰ = 81668507877211 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8166850787819 + ... + 8166850787828.

It is an arithmetic number, because the mean of its divisors is an integer number (24500552363472).

Almost surely, 2^{81668507878235} is an apocalyptic number.

81668507878235 is a deficient number, since it is larger than the sum of its proper divisors (16333701575653).

81668507878235 is a wasteful number, since it uses less digits than its factorization.

81668507878235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16333701575652.

The product of its (nonzero) digits is 1083801600, while the sum is 74.

The spelling of 81668507878235 in words is "eighty-one trillion, six hundred sixty-eight billion, five hundred seven million, eight hundred seventy-eight thousand, two hundred thirty-five".