644239 has 2 divisors, whose sum is σ = 644240. Its totient is φ = 644238.

The previous prime is 644227. The next prime is 644257. The reversal of 644239 is 932446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644239 - 2¹⁷ = 513167 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (641239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322119 + 322120.

It is an arithmetic number, because the mean of its divisors is an integer number (322120).

2⁶⁴⁴²³⁹ is an apocalyptic number.

644239 is a deficient number, since it is larger than the sum of its proper divisors (1).

644239 is an equidigital number, since it uses as much as digits as its factorization.

644239 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 28.

The square root of 644239 is about 802.6450024762. The cubic root of 644239 is about 86.3672325876.

The spelling of 644239 in words is "six hundred forty-four thousand, two hundred thirty-nine".