664409839 has 4 divisors (see below), whose sum is σ = 664461856. Its totient is φ = 664357824.

The previous prime is 664409821. The next prime is 664409881. The reversal of 664409839 is 938904466.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 664409839 - 2¹⁵ = 664377071 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 664409792 and 664409801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664409819) 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, 7807 + ... + 37279.

It is an arithmetic number, because the mean of its divisors is an integer number (166115464).

Almost surely, 2^664409839 is an apocalyptic number.

664409839 is a deficient number, since it is larger than the sum of its proper divisors (52017).

664409839 is a wasteful number, since it uses less digits than its factorization.

664409839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52016.

The product of its (nonzero) digits is 1119744, while the sum is 49.

The square root of 664409839 is about 25776.1486455987. The cubic root of 664409839 is about 872.5935900131.

The spelling of 664409839 in words is "six hundred sixty-four million, four hundred nine thousand, eight hundred thirty-nine".