644226266 has 4 divisors (see below), whose sum is σ = 966339402. Its totient is φ = 322113132.

The previous prime is 644226263. The next prime is 644226281. The reversal of 644226266 is 662622446.

It is a happy number.

644226266 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 557196025 + 87030241 = 23605^2 + 9329^2 .

It is not an unprimeable number, because it can be changed into a prime (644226263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161056565 + ... + 161056568.

Almost surely, 2^644226266 is an apocalyptic number.

644226266 is a deficient number, since it is larger than the sum of its proper divisors (322113136).

644226266 is a wasteful number, since it uses less digits than its factorization.

644226266 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322113135.

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

The square root of 644226266 is about 25381.6127541179. The cubic root of 644226266 is about 863.6666354019. Note that the first 4 decimals are identical.

The spelling of 644226266 in words is "six hundred forty-four million, two hundred twenty-six thousand, two hundred sixty-six".