644530001 has 2 divisors, whose sum is σ = 644530002. Its totient is φ = 644530000.

The previous prime is 644529929. The next prime is 644530013. The reversal of 644530001 is 100035446.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 583705600 + 60824401 = 24160^2 + 7799^2 .

It is a cyclic number.

It is not a de Polignac number, because 644530001 - 2²² = 640335697 is a prime.

It is not a weakly prime, because it can be changed into another prime (644530301) 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 as a sum of consecutive naturals, namely, 322265000 + 322265001.

It is an arithmetic number, because the mean of its divisors is an integer number (322265001).

Almost surely, 2^644530001 is an apocalyptic number.

It is an amenable number.

644530001 is a deficient number, since it is larger than the sum of its proper divisors (1).

644530001 is an equidigital number, since it uses as much as digits as its factorization.

644530001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 644530001 is about 25387.5954158719. The cubic root of 644530001 is about 863.8023457797.

Adding to 644530001 its reverse (100035446), we get a palindrome (744565447).

The spelling of 644530001 in words is "six hundred forty-four million, five hundred thirty thousand, one".