1666564447 has 4 divisors (see below), whose sum is σ = 1673537760. Its totient is φ = 1659591136.

The previous prime is 1666564439. The next prime is 1666564507. The reversal of 1666564447 is 7444656661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1666564447 - 2³ = 1666564439 is a prime.

It is a super-3 number, since 3×1666564447³ (a number of 29 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1666564447.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666568447) by changing a digit.

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, 3486298 + ... + 3486775.

It is an arithmetic number, because the mean of its divisors is an integer number (418384440).

Almost surely, 2^1666564447 is an apocalyptic number.

1666564447 is a deficient number, since it is larger than the sum of its proper divisors (6973313).

1666564447 is an equidigital number, since it uses as much as digits as its factorization.

1666564447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6973312.

The product of its digits is 2903040, while the sum is 49.

The square root of 1666564447 is about 40823.5770970649. The cubic root of 1666564447 is about 1185.6068620379.

The spelling of 1666564447 in words is "one billion, six hundred sixty-six million, five hundred sixty-four thousand, four hundred forty-seven".