66612711721666 has 16 divisors (see below), whose sum is σ = 109006167741120. Its totient is φ = 30277519616880.

The previous prime is 66612711721583. The next prime is 66612711721679.

It is a happy number.

66612711721666 is nontrivially palindromic in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 66612711721666.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48594201 + ... + 49946188.

It is an arithmetic number, because the mean of its divisors is an integer number (6812885483820).

Almost surely, 2^{66612711721666} is an apocalyptic number.

66612711721666 is a deficient number, since it is larger than the sum of its proper divisors (42393456019454).

66612711721666 is a wasteful number, since it uses less digits than its factorization.

66612711721666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98571129.

The product of its digits is 9144576, while the sum is 58.

The spelling of 66612711721666 in words is "sixty-six trillion, six hundred twelve billion, seven hundred eleven million, seven hundred twenty-one thousand, six hundred sixty-six".