644609236 has 6 divisors (see below), whose sum is σ = 1128066170. Its totient is φ = 322304616.

The previous prime is 644609233. The next prime is 644609239. The reversal of 644609236 is 632906446.

It is an interprime number because it is at equal distance from previous prime (644609233) and next prime (644609239).

It can be written as a sum of positive squares in only one way, i.e., 561690000 + 82919236 = 23700^2 + 9106^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644609233) by changing a digit.

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 as a sum of consecutive naturals, namely, 80576151 + ... + 80576158.

Almost surely, 2^644609236 is an apocalyptic number.

It is an amenable number.

644609236 is a deficient number, since it is larger than the sum of its proper divisors (483456934).

644609236 is a wasteful number, since it uses less digits than its factorization.

644609236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161152313 (or 161152311 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 40.

The square root of 644609236 is about 25389.1558741129. The cubic root of 644609236 is about 863.8377413777.

The spelling of 644609236 in words is "six hundred forty-four million, six hundred nine thousand, two hundred thirty-six".