644302643 has 4 divisors (see below), whose sum is σ = 649005720. Its totient is φ = 639599568.

The previous prime is 644302639. The next prime is 644302663. The reversal of 644302643 is 346203446.

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 644302643 - 2² = 644302639 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644302663) 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, 2351333 + ... + 2351606.

It is an arithmetic number, because the mean of its divisors is an integer number (162251430).

Almost surely, 2^644302643 is an apocalyptic number.

644302643 is a deficient number, since it is larger than the sum of its proper divisors (4703077).

644302643 is a wasteful number, since it uses less digits than its factorization.

644302643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4703076.

The product of its (nonzero) digits is 41472, while the sum is 32.

The square root of 644302643 is about 25383.1172829501. The cubic root of 644302643 is about 863.7007650566.

The spelling of 644302643 in words is "six hundred forty-four million, three hundred two thousand, six hundred forty-three".