644054491 has 2 divisors, whose sum is σ = 644054492. Its totient is φ = 644054490.

The previous prime is 644054479. The next prime is 644054573. The reversal of 644054491 is 194450446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644054491 - 2⁵ = 644054459 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644054491.

It is not a weakly prime, because it can be changed into another prime (644054431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322027245 + 322027246.

It is an arithmetic number, because the mean of its divisors is an integer number (322027246).

Almost surely, 2^644054491 is an apocalyptic number.

644054491 is a deficient number, since it is larger than the sum of its proper divisors (1).

644054491 is an equidigital number, since it uses as much as digits as its factorization.

644054491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69120, while the sum is 37.

The square root of 644054491 is about 25378.2286812929. The cubic root of 644054491 is about 863.5898665544.

The spelling of 644054491 in words is "six hundred forty-four million, fifty-four thousand, four hundred ninety-one".