1665665606601 has 10 divisors (see below), whose sum is σ = 2488216523562. Its totient is φ = 1110443737680.

The previous prime is 1665665606599. The next prime is 1665665606723. The reversal of 1665665606601 is 1066065665661.

1665665606601 is a `hidden beast` number, since 16 + 6 + 5 + 6 + 6 + 560 + 6 + 60 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1408373189001 + 257292417600 = 1186749^2 + 507240^2 .

It is not a de Polignac number, because 1665665606601 - 2¹ = 1665665606599 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1665665601601) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 10281886380 + ... + 10281886541.

Almost surely, 2^{1665665606601} is an apocalyptic number.

It is an amenable number.

1665665606601 is a deficient number, since it is larger than the sum of its proper divisors (822550916961).

1665665606601 is an equidigital number, since it uses as much as digits as its factorization.

1665665606601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20563772933 (or 20563772924 counting only the distinct ones).

The product of its (nonzero) digits is 6998400, while the sum is 54.

The spelling of 1665665606601 in words is "one trillion, six hundred sixty-five billion, six hundred sixty-five million, six hundred six thousand, six hundred one".