644576620 has 24 divisors (see below), whose sum is σ = 1400288400. Its totient is φ = 248939712.

The previous prime is 644576617. The next prime is 644576629. The reversal of 644576620 is 26675446.

It is not an unprimeable number, because it can be changed into a prime (644576629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 555090 + ... + 556249.

It is an arithmetic number, because the mean of its divisors is an integer number (58345350).

Almost surely, 2^644576620 is an apocalyptic number.

It is an amenable number.

644576620 is an abundant number, since it is smaller than the sum of its proper divisors (755711780).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644576620 is a wasteful number, since it uses less digits than its factorization.

644576620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1111377 (or 1111375 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 40.

The square root of 644576620 is about 25388.5135445146. The cubic root of 644576620 is about 863.8231716170.

The spelling of 644576620 in words is "six hundred forty-four million, five hundred seventy-six thousand, six hundred twenty".