644353650 has 96 divisors (see below), whose sum is σ = 1869076800. Its totient is φ = 162777600.

The previous prime is 644353643. The next prime is 644353657. The reversal of 644353650 is 56353446.

644353650 is a `hidden beast` number, since 644 + 3 + 5 + 3 + 6 + 5 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (644353643) and next prime (644353657).

It is not an unprimeable number, because it can be changed into a prime (644353657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 13090 + ... + 38210.

It is an arithmetic number, because the mean of its divisors is an integer number (19469550).

Almost surely, 2^644353650 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644353650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (934538400).

644353650 is an abundant number, since it is smaller than the sum of its proper divisors (1224723150).

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

644353650 is a wasteful number, since it uses less digits than its factorization.

644353650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25161 (or 25150 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 36.

The square root of 644353650 is about 25384.1220056948. The cubic root of 644353650 is about 863.7235564280.

The spelling of 644353650 in words is "six hundred forty-four million, three hundred fifty-three thousand, six hundred fifty".