1661055666 has 8 divisors (see below), whose sum is σ = 3322111344. Its totient is φ = 553685220.

The previous prime is 1661055637. The next prime is 1661055667. The reversal of 1661055666 is 6665501661.

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

1661055666 is an admirable number.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1661055667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138421300 + ... + 138421311.

It is an arithmetic number, because the mean of its divisors is an integer number (415263918).

Almost surely, 2^1661055666 is an apocalyptic number.

1661055666 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.

1661055666 is a wasteful number, since it uses less digits than its factorization.

1661055666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276842616.

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

The square root of 1661055666 is about 40756.0506673549. The cubic root of 1661055666 is about 1184.2990902131.

The spelling of 1661055666 in words is "one billion, six hundred sixty-one million, fifty-five thousand, six hundred sixty-six".