1664123206 has 4 divisors (see below), whose sum is σ = 2496184812. Its totient is φ = 832061602.

The previous prime is 1664123179. The next prime is 1664123207. The reversal of 1664123206 is 6023214661.

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

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664123207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 416030800 + ... + 416030803.

It is an arithmetic number, because the mean of its divisors is an integer number (624046203).

Almost surely, 2^1664123206 is an apocalyptic number.

1664123206 is a deficient number, since it is larger than the sum of its proper divisors (832061606).

1664123206 is an equidigital number, since it uses as much as digits as its factorization.

1664123206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832061605.

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 1664123206 is about 40793.6662485734. Note that the first 3 decimals coincide. The cubic root of 1664123206 is about 1185.0276732189.

Adding to 1664123206 its reverse (6023214661), we get a palindrome (7687337867).

The spelling of 1664123206 in words is "one billion, six hundred sixty-four million, one hundred twenty-three thousand, two hundred six".