644296620 has 192 divisors, whose sum is σ = 2035321344. Its totient is φ = 150958080.

The previous prime is 644296607. The next prime is 644296643. The reversal of 644296620 is 26692446.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 3952659 + ... + 3952821.

It is an arithmetic number, because the mean of its divisors is an integer number (10600632).

Almost surely, 2^644296620 is an apocalyptic number.

644296620 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644296620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1017660672).

644296620 is an abundant number, since it is smaller than the sum of its proper divisors (1391024724).

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

644296620 is a wasteful number, since it uses less digits than its factorization.

644296620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 352 (or 350 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 39.

The square root of 644296620 is about 25382.9986408226. The cubic root of 644296620 is about 863.6980737303.

The spelling of 644296620 in words is "six hundred forty-four million, two hundred ninety-six thousand, six hundred twenty".