1666561506 has 16 divisors (see below), whose sum is σ = 3336277248. Its totient is φ = 554994800.

The previous prime is 1666561483. The next prime is 1666561553. The reversal of 1666561506 is 6051656661.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 124530 + ... + 137261.

It is an arithmetic number, because the mean of its divisors is an integer number (208517328).

Almost surely, 2^1666561506 is an apocalyptic number.

1666561506 is an abundant number, since it is smaller than the sum of its proper divisors (1669715742).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1666561506 is a wasteful number, since it uses less digits than its factorization.

1666561506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262857.

The product of its (nonzero) digits is 194400, while the sum is 42.

The square root of 1666561506 is about 40823.5410761977. The cubic root of 1666561506 is about 1185.6061646208.

The spelling of 1666561506 in words is "one billion, six hundred sixty-six million, five hundred sixty-one thousand, five hundred six".