644074009 has 2 divisors, whose sum is σ = 644074010. Its totient is φ = 644074008.

The previous prime is 644073979. The next prime is 644074049. The reversal of 644074009 is 900470446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 586995984 + 57078025 = 24228^2 + 7555^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644074009 is a prime.

It is not a weakly prime, because it can be changed into another prime (644074049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322037004 + 322037005.

It is an arithmetic number, because the mean of its divisors is an integer number (322037005).

Almost surely, 2^644074009 is an apocalyptic number.

It is an amenable number.

644074009 is a deficient number, since it is larger than the sum of its proper divisors (1).

644074009 is an equidigital number, since it uses as much as digits as its factorization.

644074009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 34.

The square root of 644074009 is about 25378.6132205840. The cubic root of 644074009 is about 863.5985901313.

The spelling of 644074009 in words is "six hundred forty-four million, seventy-four thousand, nine".