644868446 has 8 divisors (see below), whose sum is σ = 1024202880. Its totient is φ = 303467488.

The previous prime is 644868439. The next prime is 644868481.

644868446 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 644868394 and 644868403.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9483326 + ... + 9483393.

It is an arithmetic number, because the mean of its divisors is an integer number (128025360).

Almost surely, 2^644868446 is an apocalyptic number.

644868446 is a deficient number, since it is larger than the sum of its proper divisors (379334434).

644868446 is a wasteful number, since it uses less digits than its factorization.

644868446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18966738.

The product of its digits is 3538944, while the sum is 50.

The square root of 644868446 is about 25394.2600994792. The cubic root of 644868446 is about 863.9535145529.

The spelling of 644868446 in words is "six hundred forty-four million, eight hundred sixty-eight thousand, four hundred forty-six".