66747555621605 has 16 divisors (see below), whose sum is σ = 81416580319344. Its totient is φ = 52518507425280.

The previous prime is 66747555621587. The next prime is 66747555621631. The reversal of 66747555621605 is 50612655574766.

It can be written as a sum of positive squares in 8 ways, for example, as 11468910550084 + 55278645071521 = 3386578^2 + 7434961^2 .

It is a de Polignac number, because none of the positive numbers 2^k-66747555621605 is a prime.

It is a Smith number, since the sum of its digits (65) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4804592 + ... + 12513161.

It is an arithmetic number, because the mean of its divisors is an integer number (5088536269959).

Almost surely, 2^{66747555621605} is an apocalyptic number.

It is an amenable number.

66747555621605 is a deficient number, since it is larger than the sum of its proper divisors (14669024697739).

66747555621605 is a wasteful number, since it uses less digits than its factorization.

66747555621605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17330456.

The product of its (nonzero) digits is 317520000, while the sum is 65.

The spelling of 66747555621605 in words is "sixty-six trillion, seven hundred forty-seven billion, five hundred fifty-five million, six hundred twenty-one thousand, six hundred five".