644623634 has 8 divisors (see below), whose sum is σ = 973993788. Its totient is φ = 319959040.

The previous prime is 644623633. The next prime is 644623699. The reversal of 644623634 is 436326446.

It can be written as a sum of positive squares in 2 ways, for example, as 607474609 + 37149025 = 24647^2 + 6095^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×644623634² = 831079259022731912, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (644623633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1176047 + ... + 1176594.

Almost surely, 2^644623634 is an apocalyptic number.

644623634 is a deficient number, since it is larger than the sum of its proper divisors (329370154).

644623634 is a wasteful number, since it uses less digits than its factorization.

644623634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2352780.

The product of its digits is 248832, while the sum is 38.

The square root of 644623634 is about 25389.4394187820. The cubic root of 644623634 is about 863.8441728934.

The spelling of 644623634 in words is "six hundred forty-four million, six hundred twenty-three thousand, six hundred thirty-four".