1666221663 has 32 divisors (see below), whose sum is σ = 2533766400. Its totient is φ = 967389696.

The previous prime is 1666221653. The next prime is 1666221691. The reversal of 1666221663 is 3661226661.

It is not a de Polignac number, because 1666221663 - 2⁵ = 1666221631 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666221643) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21673 + ... + 61661.

It is an arithmetic number, because the mean of its divisors is an integer number (79180200).

Almost surely, 2^1666221663 is an apocalyptic number.

1666221663 is a deficient number, since it is larger than the sum of its proper divisors (867544737).

1666221663 is a wasteful number, since it uses less digits than its factorization.

1666221663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40071.

The product of its digits is 93312, while the sum is 39.

The square root of 1666221663 is about 40819.3785229516. The cubic root of 1666221663 is about 1185.5255700663.

The spelling of 1666221663 in words is "one billion, six hundred sixty-six million, two hundred twenty-one thousand, six hundred sixty-three".