644225066 has 16 divisors (see below), whose sum is σ = 980919720. Its totient is φ = 317284800.

The previous prime is 644225027. The next prime is 644225069. The reversal of 644225066 is 660522446.

It can be written as a sum of positive squares in 4 ways, for example, as 616082041 + 28143025 = 24821^2 + 5305^2 .

It is not an unprimeable number, because it can be changed into a prime (644225069) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31700 + ... + 47888.

Almost surely, 2^644225066 is an apocalyptic number.

644225066 is a deficient number, since it is larger than the sum of its proper divisors (336694654).

644225066 is a wasteful number, since it uses less digits than its factorization.

644225066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16489.

The product of its (nonzero) digits is 69120, while the sum is 35.

The square root of 644225066 is about 25381.5891149471. The cubic root of 644225066 is about 863.6660991511. Note that the first 3 decimals are identical.

The spelling of 644225066 in words is "six hundred forty-four million, two hundred twenty-five thousand, sixty-six".