66501605543 has 4 divisors (see below), whose sum is σ = 66603446328. Its totient is φ = 66399764760.

The previous prime is 66501605509. The next prime is 66501605549. The reversal of 66501605543 is 34550610566.

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 66501605543 - 2²⁶ = 66434496679 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66501605543.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66501605549) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50919413 + ... + 50920718.

It is an arithmetic number, because the mean of its divisors is an integer number (16650861582).

Almost surely, 2^66501605543 is an apocalyptic number.

66501605543 is a deficient number, since it is larger than the sum of its proper divisors (101840785).

66501605543 is a wasteful number, since it uses less digits than its factorization.

66501605543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101840784.

The product of its (nonzero) digits is 324000, while the sum is 41.

The spelling of 66501605543 in words is "sixty-six billion, five hundred one million, six hundred five thousand, five hundred forty-three".