644030557 has 2 divisors, whose sum is σ = 644030558. Its totient is φ = 644030556.

The previous prime is 644030477. The next prime is 644030573. The reversal of 644030557 is 755030446.

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., 383337241 + 260693316 = 19579^2 + 16146^2 .

It is a cyclic number.

It is not a de Polignac number, because 644030557 - 2¹¹ = 644028509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644034557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322015278 + 322015279.

It is an arithmetic number, because the mean of its divisors is an integer number (322015279).

Almost surely, 2^644030557 is an apocalyptic number.

It is an amenable number.

644030557 is a deficient number, since it is larger than the sum of its proper divisors (1).

644030557 is an equidigital number, since it uses as much as digits as its factorization.

644030557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 50400, while the sum is 34.

The square root of 644030557 is about 25377.7571309996. The cubic root of 644030557 is about 863.5791690041.

The spelling of 644030557 in words is "six hundred forty-four million, thirty thousand, five hundred fifty-seven".