644544653 has 8 divisors (see below), whose sum is σ = 665688576. Its totient is φ = 623422800.

The previous prime is 644544643. The next prime is 644544671. The reversal of 644544653 is 356445446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644544653 - 2¹² = 644540557 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 644544653.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644544643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 70823 + ... + 79403.

It is an arithmetic number, because the mean of its divisors is an integer number (83211072).

Almost surely, 2^644544653 is an apocalyptic number.

It is an amenable number.

644544653 is a deficient number, since it is larger than the sum of its proper divisors (21143923).

644544653 is a wasteful number, since it uses less digits than its factorization.

644544653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11035.

The product of its digits is 691200, while the sum is 41.

The square root of 644544653 is about 25387.8839803557. The cubic root of 644544653 is about 863.8088912915.

The spelling of 644544653 in words is "six hundred forty-four million, five hundred forty-four thousand, six hundred fifty-three".