1666605565 has 8 divisors (see below), whose sum is σ = 2001055320. Its totient is φ = 1332532032.

The previous prime is 1666605547. The next prime is 1666605569. The reversal of 1666605565 is 5655066661.

It can be written as a sum of positive squares in 4 ways, for example, as 206295769 + 1460309796 = 14363^2 + 38214^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 1666605565 - 2⁵ = 1666605533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666605569) 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, 84214 + ... + 102103.

It is an arithmetic number, because the mean of its divisors is an integer number (250131915).

Almost surely, 2^1666605565 is an apocalyptic number.

It is an amenable number.

1666605565 is a deficient number, since it is larger than the sum of its proper divisors (334449755).

1666605565 is a wasteful number, since it uses less digits than its factorization.

1666605565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188111.

The product of its (nonzero) digits is 972000, while the sum is 46.

The square root of 1666605565 is about 40824.0806999986. The cubic root of 1666605565 is about 1185.6166125124.

It can be divided in two parts, 166660 and 5565, that added together give a square (172225 = 415²).

The spelling of 1666605565 in words is "one billion, six hundred sixty-six million, six hundred five thousand, five hundred sixty-five".