643616444 has 6 divisors (see below), whose sum is σ = 1126328784. Its totient is φ = 321808220.

The previous prime is 643616423. The next prime is 643616461. The reversal of 643616444 is 444616346.

It is a junction number, because it is equal to n+sod(n) for n = 643616398 and 643616407.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80452052 + ... + 80452059.

It is an arithmetic number, because the mean of its divisors is an integer number (187721464).

Almost surely, 2^643616444 is an apocalyptic number.

It is an amenable number.

643616444 is a deficient number, since it is larger than the sum of its proper divisors (482712340).

643616444 is a wasteful number, since it uses less digits than its factorization.

643616444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160904115 (or 160904113 counting only the distinct ones).

The product of its digits is 165888, while the sum is 38.

The square root of 643616444 is about 25369.5968434660. The cubic root of 643616444 is about 863.3940349118.

The spelling of 643616444 in words is "six hundred forty-three million, six hundred sixteen thousand, four hundred forty-four".