39664813 has 4 divisors (see below), whose sum is σ = 39707388. Its totient is φ = 39622240.

The previous prime is 39664771. The next prime is 39664817. The reversal of 39664813 is 31846693.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31846693 = 53 ⋅600881.

It can be written as a sum of positive squares in 2 ways, for example, as 16499844 + 23164969 = 4062^2 + 4813^2 .

It is a cyclic number.

It is not a de Polignac number, because 39664813 - 2⁹ = 39664301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39664817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19858 + ... + 21763.

It is an arithmetic number, because the mean of its divisors is an integer number (9926847).

Almost surely, 2^39664813 is an apocalyptic number.

It is an amenable number.

39664813 is a deficient number, since it is larger than the sum of its proper divisors (42575).

39664813 is an equidigital number, since it uses as much as digits as its factorization.

39664813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42574.

The product of its digits is 93312, while the sum is 40.

The square root of 39664813 is about 6298.0007145125. Note that the first 3 decimals coincide. The cubic root of 39664813 is about 341.0372390482.

The spelling of 39664813 in words is "thirty-nine million, six hundred sixty-four thousand, eight hundred thirteen".