1664993906 has 16 divisors (see below), whose sum is σ = 2645163864. Its totient is φ = 783300864.

The previous prime is 1664993899. The next prime is 1664993929. The reversal of 1664993906 is 6093994661.

It can be written as a sum of positive squares in 4 ways, for example, as 967769881 + 697224025 = 31109^2 + 26405^2 .

It is a Curzon number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 205916 + ... + 213848.

Almost surely, 2^1664993906 is an apocalyptic number.

1664993906 is a deficient number, since it is larger than the sum of its proper divisors (980169958).

1664993906 is a wasteful number, since it uses less digits than its factorization.

1664993906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14125.

The product of its (nonzero) digits is 1889568, while the sum is 53.

The square root of 1664993906 is about 40804.3368528396. The cubic root of 1664993906 is about 1185.2343133064.

The spelling of 1664993906 in words is "one billion, six hundred sixty-four million, nine hundred ninety-three thousand, nine hundred six".