66818915523 has 24 divisors (see below), whose sum is σ = 100233924336. Its totient is φ = 44482284000.

The previous prime is 66818915509. The next prime is 66818915539. The reversal of 66818915523 is 32551981866.

66818915523 is a `hidden beast` number, since 6 + 6 + 8 + 1 + 89 + 1 + 552 + 3 = 666.

It is not a de Polignac number, because 66818915523 - 2⁴ = 66818915507 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66818915523.

It is not an unprimeable number, because it can be changed into a prime (66818915563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 25788 + ... + 366473.

It is an arithmetic number, because the mean of its divisors is an integer number (4176413514).

Almost surely, 2^66818915523 is an apocalyptic number.

66818915523 is a deficient number, since it is larger than the sum of its proper divisors (33415008813).

66818915523 is an equidigital number, since it uses as much as digits as its factorization.

66818915523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392977 (or 392965 counting only the distinct ones).

The product of its digits is 3110400, while the sum is 54.

The spelling of 66818915523 in words is "sixty-six billion, eight hundred eighteen million, nine hundred fifteen thousand, five hundred twenty-three".