644043053 has 4 divisors (see below), whose sum is σ = 661449660. Its totient is φ = 626636448.

The previous prime is 644043041. The next prime is 644043067. The reversal of 644043053 is 350340446.

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 576096004 + 67947049 = 24002^2 + 8243^2 .

It is a cyclic number.

It is not a de Polignac number, because 644043053 - 2⁸ = 644042797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644043083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8703248 + ... + 8703321.

It is an arithmetic number, because the mean of its divisors is an integer number (165362415).

Almost surely, 2^644043053 is an apocalyptic number.

It is an amenable number.

644043053 is a deficient number, since it is larger than the sum of its proper divisors (17406607).

644043053 is a wasteful number, since it uses less digits than its factorization.

644043053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17406606.

The product of its (nonzero) digits is 17280, while the sum is 29.

The square root of 644043053 is about 25378.0033296554. The cubic root of 644043053 is about 863.5847542543.

Adding to 644043053 its reverse (350340446), we get a palindrome (994383499).

The spelling of 644043053 in words is "six hundred forty-four million, forty-three thousand, fifty-three".