644475850 has 12 divisors (see below), whose sum is σ = 1198725174. Its totient is φ = 257790320.

The previous prime is 644475823. The next prime is 644475869. The reversal of 644475850 is 58574446.

It can be written as a sum of positive squares in 3 ways, for example, as 250810569 + 393665281 = 15837^2 + 19841^2 .

It is a junction number, because it is equal to n+sod(n) for n = 644475797 and 644475806.

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 in 5 ways as a sum of consecutive naturals, for example, 6444709 + ... + 6444808.

Almost surely, 2^644475850 is an apocalyptic number.

644475850 is a deficient number, since it is larger than the sum of its proper divisors (554249324).

644475850 is a wasteful number, since it uses less digits than its factorization.

644475850 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12889529 (or 12889524 counting only the distinct ones).

The product of its (nonzero) digits is 537600, while the sum is 43.

The square root of 644475850 is about 25386.5289080646. The cubic root of 644475850 is about 863.7781539548.

The spelling of 644475850 in words is "six hundred forty-four million, four hundred seventy-five thousand, eight hundred fifty".