644821325 has 24 divisors (see below), whose sum is σ = 819322560. Its totient is φ = 503254400.

The previous prime is 644821321. The next prime is 644821327. The reversal of 644821325 is 523128446.

It is not a de Polignac number, because 644821325 - 2² = 644821321 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644821321) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 200480 + ... + 203670.

It is an arithmetic number, because the mean of its divisors is an integer number (34138440).

Almost surely, 2^644821325 is an apocalyptic number.

It is an amenable number.

644821325 is a deficient number, since it is larger than the sum of its proper divisors (174501235).

644821325 is a wasteful number, since it uses less digits than its factorization.

644821325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3397 (or 3392 counting only the distinct ones).

The product of its digits is 46080, while the sum is 35.

The square root of 644821325 is about 25393.3322941279. The cubic root of 644821325 is about 863.9324708060.

The spelling of 644821325 in words is "six hundred forty-four million, eight hundred twenty-one thousand, three hundred twenty-five".