644447 has 2 divisors, whose sum is σ = 644448. Its totient is φ = 644446.

The previous prime is 644443. The next prime is 644489. The reversal of 644447 is 744446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644447 - 2² = 644443 is a prime.

It is an Ulam number.

It is a plaindrome in base 14.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644443) 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, 322223 + 322224.

It is an arithmetic number, because the mean of its divisors is an integer number (322224).

2⁶⁴⁴⁴⁴⁷ is an apocalyptic number.

644447 is a deficient number, since it is larger than the sum of its proper divisors (1).

644447 is an equidigital number, since it uses as much as digits as its factorization.

644447 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10752, while the sum is 29.

The square root of 644447 is about 802.7745636229. The cubic root of 644447 is about 86.3765264736.

Subtracting 644447 from its reverse (744446), we obtain a palindrome (99999).

The spelling of 644447 in words is "six hundred forty-four thousand, four hundred forty-seven".