19664813 has 16 divisors (see below), whose sum is σ = 23585280. Its totient is φ = 16039296.

The previous prime is 19664779. The next prime is 19664833. The reversal of 19664813 is 31846691.

It is not a de Polignac number, because 19664813 - 2¹⁶ = 19599277 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19664833) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 14156 + ... + 15482.

It is an arithmetic number, because the mean of its divisors is an integer number (1474080).

Almost surely, 2^19664813 is an apocalyptic number.

It is an amenable number.

19664813 is a deficient number, since it is larger than the sum of its proper divisors (3920467).

19664813 is a wasteful number, since it uses less digits than its factorization.

19664813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1436.

The product of its digits is 31104, while the sum is 38.

The square root of 19664813 is about 4434.5025651137. The cubic root of 19664813 is about 269.9168147945.

The spelling of 19664813 in words is "nineteen million, six hundred sixty-four thousand, eight hundred thirteen".