644603 has 4 divisors (see below), whose sum is σ = 646800. Its totient is φ = 642408.

The previous prime is 644599. The next prime is 644617. The reversal of 644603 is 306446.

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 644603 - 2² = 644599 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644653) 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, 575 + ... + 1272.

It is an arithmetic number, because the mean of its divisors is an integer number (161700).

2⁶⁴⁴⁶⁰³ is an apocalyptic number.

644603 is a deficient number, since it is larger than the sum of its proper divisors (2197).

644603 is a wasteful number, since it uses less digits than its factorization.

644603 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2196.

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 644603 is about 802.8717207624. The cubic root of 644603 is about 86.3834955757.

The spelling of 644603 in words is "six hundred forty-four thousand, six hundred three".