644052521 has 12 divisors (see below), whose sum is σ = 749773440. Its totient is φ = 551625480.

The previous prime is 644052517. The next prime is 644052529. The reversal of 644052521 is 125250446.

644052521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644052521 - 2² = 644052517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644052529) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 72176 + ... + 80606.

It is an arithmetic number, because the mean of its divisors is an integer number (62481120).

Almost surely, 2^644052521 is an apocalyptic number.

It is an amenable number.

644052521 is a deficient number, since it is larger than the sum of its proper divisors (105720919).

644052521 is a wasteful number, since it uses less digits than its factorization.

644052521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10004 (or 9997 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 29.

The square root of 644052521 is about 25378.1898684678. The cubic root of 644052521 is about 863.5889860524.

The spelling of 644052521 in words is "six hundred forty-four million, fifty-two thousand, five hundred twenty-one".