1666321705 has 8 divisors (see below), whose sum is σ = 2000041992. Its totient is φ = 1332753408.

The previous prime is 1666321667. The next prime is 1666321763. The reversal of 1666321705 is 5071236661.

It can be written as a sum of positive squares in 4 ways, for example, as 353853721 + 1312467984 = 18811^2 + 36228^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 1666321705 - 2⁷ = 1666321577 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 12294 + ... + 59023.

It is an arithmetic number, because the mean of its divisors is an integer number (250005249).

Almost surely, 2^1666321705 is an apocalyptic number.

It is an amenable number.

1666321705 is a deficient number, since it is larger than the sum of its proper divisors (333720287).

1666321705 is an equidigital number, since it uses as much as digits as its factorization.

1666321705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75995.

The product of its (nonzero) digits is 45360, while the sum is 37.

The square root of 1666321705 is about 40820.6039274286. The cubic root of 1666321705 is about 1185.5492963963.

The spelling of 1666321705 in words is "one billion, six hundred sixty-six million, three hundred twenty-one thousand, seven hundred five".