644660503 has 4 divisors (see below), whose sum is σ = 644799960. Its totient is φ = 644521048.

The previous prime is 644660441. The next prime is 644660521. The reversal of 644660503 is 305066446.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644660503 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644660543) 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, 62548 + ... + 72121.

It is an arithmetic number, because the mean of its divisors is an integer number (161199990).

Almost surely, 2^644660503 is an apocalyptic number.

644660503 is a deficient number, since it is larger than the sum of its proper divisors (139457).

644660503 is a wasteful number, since it uses less digits than its factorization.

644660503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139456.

The product of its (nonzero) digits is 51840, while the sum is 34.

The square root of 644660503 is about 25390.1654779956. The cubic root of 644660503 is about 863.8606416574.

The spelling of 644660503 in words is "six hundred forty-four million, six hundred sixty thousand, five hundred three".