644080835 has 4 divisors (see below), whose sum is σ = 772897008. Its totient is φ = 515264664.

The previous prime is 644080817. The next prime is 644080837. The reversal of 644080835 is 538080446.

It is a happy number.

644080835 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 644080835 - 2⁶ = 644080771 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644080837) 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, 64408079 + ... + 64408088.

It is an arithmetic number, because the mean of its divisors is an integer number (193224252).

Almost surely, 2^644080835 is an apocalyptic number.

644080835 is a deficient number, since it is larger than the sum of its proper divisors (128816173).

644080835 is a wasteful number, since it uses less digits than its factorization.

644080835 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128816172.

The product of its (nonzero) digits is 92160, while the sum is 38.

The square root of 644080835 is about 25378.7477035412. The cubic root of 644080835 is about 863.6016409728.

The spelling of 644080835 in words is "six hundred forty-four million, eighty thousand, eight hundred thirty-five".