644631503 has 4 divisors (see below), whose sum is σ = 647200008. Its totient is φ = 642063000.

The previous prime is 644631473. The next prime is 644631509. The reversal of 644631503 is 305136446.

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

It is a cyclic number.

It is not a de Polignac number, because 644631503 - 2¹² = 644627407 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644631503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644631509) 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 in 3 ways as a sum of consecutive naturals, for example, 1283876 + ... + 1284377.

It is an arithmetic number, because the mean of its divisors is an integer number (161800002).

Almost surely, 2^644631503 is an apocalyptic number.

644631503 is a deficient number, since it is larger than the sum of its proper divisors (2568505).

644631503 is a wasteful number, since it uses less digits than its factorization.

644631503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2568504.

The product of its (nonzero) digits is 25920, while the sum is 32.

The square root of 644631503 is about 25389.5943843142. The cubic root of 644631503 is about 863.8476878964.

Adding to 644631503 its reverse (305136446), we get a palindrome (949767949).

The spelling of 644631503 in words is "six hundred forty-four million, six hundred thirty-one thousand, five hundred three".