644850653 has 4 divisors (see below), whose sum is σ = 648958140. Its totient is φ = 640743168.

The previous prime is 644850631. The next prime is 644850667. The reversal of 644850653 is 356058446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 331312804 + 313537849 = 18202^2 + 17707^2 .

It is a cyclic number.

It is not a de Polignac number, because 644850653 - 2¹⁶ = 644785117 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644850653.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644850053) 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 3 ways as a sum of consecutive naturals, for example, 2053508 + ... + 2053821.

It is an arithmetic number, because the mean of its divisors is an integer number (162239535).

Almost surely, 2^644850653 is an apocalyptic number.

It is an amenable number.

644850653 is a deficient number, since it is larger than the sum of its proper divisors (4107487).

644850653 is a wasteful number, since it uses less digits than its factorization.

644850653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4107486.

The product of its (nonzero) digits is 345600, while the sum is 41.

The square root of 644850653 is about 25393.9097619882. The cubic root of 644850653 is about 863.9455685052.

The spelling of 644850653 in words is "six hundred forty-four million, eight hundred fifty thousand, six hundred fifty-three".