644472265 has 4 divisors (see below), whose sum is σ = 773366724. Its totient is φ = 515577808.

The previous prime is 644472239. The next prime is 644472287. The reversal of 644472265 is 562274446.

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

It can be written as a sum of positive squares in 2 ways, for example, as 512750736 + 131721529 = 22644^2 + 11477^2 .

It is a cyclic number.

It is not a de Polignac number, because 644472265 - 2¹¹ = 644470217 is a prime.

It is a Duffinian 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 in 3 ways as a sum of consecutive naturals, for example, 64447222 + ... + 64447231.

It is an arithmetic number, because the mean of its divisors is an integer number (193341681).

Almost surely, 2^644472265 is an apocalyptic number.

It is an amenable number.

644472265 is a deficient number, since it is larger than the sum of its proper divisors (128894459).

644472265 is a wasteful number, since it uses less digits than its factorization.

644472265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128894458.

The product of its digits is 322560, while the sum is 40.

The square root of 644472265 is about 25386.4582996526. The cubic root of 644472265 is about 863.7765523171.

The spelling of 644472265 in words is "six hundred forty-four million, four hundred seventy-two thousand, two hundred sixty-five".