644440201 has 2 divisors, whose sum is σ = 644440202. Its totient is φ = 644440200.

The previous prime is 644440193. The next prime is 644440217. The reversal of 644440201 is 102044446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 408848400 + 235591801 = 20220^2 + 15349^2 .

It is a cyclic number.

It is not a de Polignac number, because 644440201 - 2³ = 644440193 is a prime.

It is not a weakly prime, because it can be changed into another prime (644440231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322220100 + 322220101.

It is an arithmetic number, because the mean of its divisors is an integer number (322220101).

Almost surely, 2^644440201 is an apocalyptic number.

It is an amenable number.

644440201 is a deficient number, since it is larger than the sum of its proper divisors (1).

644440201 is an equidigital number, since it uses as much as digits as its factorization.

644440201 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3072, while the sum is 25.

The square root of 644440201 is about 25385.8267740092. The cubic root of 644440201 is about 863.7622271127.

Adding to 644440201 its reverse (102044446), we get a palindrome (746484647).

The spelling of 644440201 in words is "six hundred forty-four million, four hundred forty thousand, two hundred one".