644316797 has 4 divisors (see below), whose sum is σ = 647655420. Its totient is φ = 640978176.

The previous prime is 644316793. The next prime is 644316817. The reversal of 644316797 is 797613446.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 372528601 + 271788196 = 19301^2 + 16486^2 .

It is a cyclic number.

It is not a de Polignac number, because 644316797 - 2² = 644316793 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 (644316793) 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, 1669022 + ... + 1669407.

It is an arithmetic number, because the mean of its divisors is an integer number (161913855).

Almost surely, 2^644316797 is an apocalyptic number.

It is an amenable number.

644316797 is a deficient number, since it is larger than the sum of its proper divisors (3338623).

644316797 is a wasteful number, since it uses less digits than its factorization.

644316797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3338622.

The product of its digits is 762048, while the sum is 47.

The square root of 644316797 is about 25383.3960887821. The cubic root of 644316797 is about 863.7070895850.

The spelling of 644316797 in words is "six hundred forty-four million, three hundred sixteen thousand, seven hundred ninety-seven".