644440229 has 2 divisors, whose sum is σ = 644440230. Its totient is φ = 644440228.

The previous prime is 644440219. The next prime is 644440231. The reversal of 644440229 is 922044446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 546390625 + 98049604 = 23375^2 + 9902^2 .

It is a cyclic number.

It is not a de Polignac number, because 644440229 - 2⁸ = 644439973 is a prime.

Together with 644440231, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644440219) 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, 322220114 + 322220115.

It is an arithmetic number, because the mean of its divisors is an integer number (322220115).

Almost surely, 2^644440229 is an apocalyptic number.

It is an amenable number.

644440229 is a deficient number, since it is larger than the sum of its proper divisors (1).

644440229 is an equidigital number, since it uses as much as digits as its factorization.

644440229 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 55296, while the sum is 35.

The square root of 644440229 is about 25385.8273254980. The cubic root of 644440229 is about 863.7622396225.

The spelling of 644440229 in words is "six hundred forty-four million, four hundred forty thousand, two hundred twenty-nine".