1665564613666 has 8 divisors (see below), whose sum is σ = 2505154406400. Its totient is φ = 830513144868.

The previous prime is 1665564613633. The next prime is 1665564613667. The reversal of 1665564613666 is 6663164655661.

It is a happy number.

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

It is not an unprimeable number, because it can be changed into a prime (1665564613667) 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, 1134580066 + ... + 1134581533.

It is an arithmetic number, because the mean of its divisors is an integer number (313144300800).

Almost surely, 2^{1665564613666} is an apocalyptic number.

1665564613666 is a deficient number, since it is larger than the sum of its proper divisors (839589792734).

1665564613666 is a wasteful number, since it uses less digits than its factorization.

1665564613666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2269161968.

The product of its digits is 83980800, while the sum is 61.

The spelling of 1665564613666 in words is "one trillion, six hundred sixty-five billion, five hundred sixty-four million, six hundred thirteen thousand, six hundred sixty-six".