66506505656503 has 16 divisors (see below), whose sum is σ = 77091798836736. Its totient is φ = 56702887943040.

The previous prime is 66506505656491. The next prime is 66506505656509. The reversal of 66506505656503 is 30565650560566.

66506505656503 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 66506505656503 - 2¹³ = 66506505648311 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66506505656509) 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 15 ways as a sum of consecutive naturals, for example, 628303551 + ... + 628409392.

It is an arithmetic number, because the mean of its divisors is an integer number (4818237427296).

Almost surely, 2^{66506505656503} is an apocalyptic number.

66506505656503 is a deficient number, since it is larger than the sum of its proper divisors (10585293180233).

66506505656503 is a wasteful number, since it uses less digits than its factorization.

66506505656503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1256713254.

The product of its (nonzero) digits is 72900000, while the sum is 58.

The spelling of 66506505656503 in words is "sixty-six trillion, five hundred six billion, five hundred five million, six hundred fifty-six thousand, five hundred three".