644548189 has 2 divisors, whose sum is σ = 644548190. Its totient is φ = 644548188.

The previous prime is 644548169. The next prime is 644548231. The reversal of 644548189 is 981845446.

It is a happy number.

644548189 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 578402500 + 66145689 = 24050^2 + 8133^2 .

It is a cyclic number.

It is not a de Polignac number, because 644548189 - 2⁷ = 644548061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644548169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322274094 + 322274095.

It is an arithmetic number, because the mean of its divisors is an integer number (322274095).

Almost surely, 2^644548189 is an apocalyptic number.

It is an amenable number.

644548189 is a deficient number, since it is larger than the sum of its proper divisors (1).

644548189 is an equidigital number, since it uses as much as digits as its factorization.

644548189 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1105920, while the sum is 49.

The square root of 644548189 is about 25387.9536197780. The cubic root of 644548189 is about 863.8104709196.

The spelling of 644548189 in words is "six hundred forty-four million, five hundred forty-eight thousand, one hundred eighty-nine".