644340573 has 6 divisors (see below), whose sum is σ = 930714174. Its totient is φ = 429560376.

The previous prime is 644340569. The next prime is 644340581. The reversal of 644340573 is 375043446.

It is a happy number.

644340573 is a `hidden beast` number, since 6 + 4 + 43 + 40 + 573 = 666.

It can be written as a sum of positive squares in only one way, i.e., 640191204 + 4149369 = 25302^2 + 2037^2 .

It is not a de Polignac number, because 644340573 - 2² = 644340569 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644340583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35796690 + ... + 35796707.

It is an arithmetic number, because the mean of its divisors is an integer number (155119029).

Almost surely, 2^644340573 is an apocalyptic number.

It is an amenable number.

644340573 is a deficient number, since it is larger than the sum of its proper divisors (286373601).

644340573 is a wasteful number, since it uses less digits than its factorization.

644340573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71593403 (or 71593400 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 36.

The square root of 644340573 is about 25383.8644221088. The cubic root of 644340573 is about 863.7177133689.

The spelling of 644340573 in words is "six hundred forty-four million, three hundred forty thousand, five hundred seventy-three".