643626844 has 12 divisors (see below), whose sum is σ = 1287253744. Its totient is φ = 275840064.

The previous prime is 643626839. The next prime is 643626889. The reversal of 643626844 is 448626346.

643626844 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 643626844.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11493309 + ... + 11493364.

Almost surely, 2^643626844 is an apocalyptic number.

It is an amenable number.

643626844 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

643626844 is a wasteful number, since it uses less digits than its factorization.

643626844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22986684 (or 22986682 counting only the distinct ones).

The product of its digits is 663552, while the sum is 43.

The square root of 643626844 is about 25369.8018123910. The cubic root of 643626844 is about 863.3986853262.

The spelling of 643626844 in words is "six hundred forty-three million, six hundred twenty-six thousand, eight hundred forty-four".