1666651565649 has 8 divisors (see below), whose sum is σ = 2539659528640. Its totient is φ = 952372323216.

The previous prime is 1666651565617. The next prime is 1666651565669. The reversal of 1666651565649 is 9465651566661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1666651565649 - 2⁵ = 1666651565617 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 1666651565649.

It is not an unprimeable number, because it can be changed into a prime (1666651565669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39682180114 + ... + 39682180155.

It is an arithmetic number, because the mean of its divisors is an integer number (317457441080).

Almost surely, 2^{1666651565649} is an apocalyptic number.

It is an amenable number.

1666651565649 is a deficient number, since it is larger than the sum of its proper divisors (873007962991).

1666651565649 is an equidigital number, since it uses as much as digits as its factorization.

1666651565649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79364360279.

The product of its digits is 209952000, while the sum is 66.

The spelling of 1666651565649 in words is "one trillion, six hundred sixty-six billion, six hundred fifty-one million, five hundred sixty-five thousand, six hundred forty-nine".