644144377 has 2 divisors, whose sum is σ = 644144378. Its totient is φ = 644144376.

The previous prime is 644144363. The next prime is 644144401. The reversal of 644144377 is 773441446.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 597509136 + 46635241 = 24444^2 + 6829^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644144377 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644144357) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322072188 + 322072189.

It is an arithmetic number, because the mean of its divisors is an integer number (322072189).

Almost surely, 2^644144377 is an apocalyptic number.

It is an amenable number.

644144377 is a deficient number, since it is larger than the sum of its proper divisors (1).

644144377 is an equidigital number, since it uses as much as digits as its factorization.

644144377 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 225792, while the sum is 40.

The square root of 644144377 is about 25379.9995468873. Note that the first 3 decimals coincide. The cubic root of 644144377 is about 863.6300396706.

The spelling of 644144377 in words is "six hundred forty-four million, one hundred forty-four thousand, three hundred seventy-seven".