644966503 has 4 divisors (see below), whose sum is σ = 659965768. Its totient is φ = 629967240.

The previous prime is 644966473. The next prime is 644966513. The reversal of 644966503 is 305669446.

644966503 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 is a cyclic number.

It is not a de Polignac number, because 644966503 - 2⁹ = 644965991 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43), and also a Moran number because the ratio is a prime number: 14999221 = 644966503 / (6 + 4 + 4 + 9 + 6 + 6 + 5 + 0 + 3).

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 644966503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644966513) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7499568 + ... + 7499653.

It is an arithmetic number, because the mean of its divisors is an integer number (164991442).

Almost surely, 2^644966503 is an apocalyptic number.

644966503 is a deficient number, since it is larger than the sum of its proper divisors (14999265).

644966503 is a wasteful number, since it uses less digits than its factorization.

644966503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14999264.

The product of its (nonzero) digits is 466560, while the sum is 43.

The square root of 644966503 is about 25396.1907182947. The cubic root of 644966503 is about 863.9973025000.

The spelling of 644966503 in words is "six hundred forty-four million, nine hundred sixty-six thousand, five hundred three".