1666651566 has 8 divisors (see below), whose sum is σ = 3333303144. Its totient is φ = 555550520.

The previous prime is 1666651487. The next prime is 1666651583. The reversal of 1666651566 is 6651566661.

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

1666651566 is an admirable number.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 138887625 + ... + 138887636.

It is an arithmetic number, because the mean of its divisors is an integer number (416662893).

Almost surely, 2^1666651566 is an apocalyptic number.

1666651566 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

1666651566 is a wasteful number, since it uses less digits than its factorization.

1666651566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277775266.

The product of its digits is 1166400, while the sum is 48.

The square root of 1666651566 is about 40824.6441013268. The cubic root of 1666651566 is about 1185.6275207219.

The spelling of 1666651566 in words is "one billion, six hundred sixty-six million, six hundred fifty-one thousand, five hundred sixty-six".